{"product_id":"speras-m4-flashlight-21700-battery-extension-body","title":"SPERAS M4 v3 21700 Battery Tube | Extended Runtime","description":"\u003cstyle\u003e\n    \/* 基础排版优化 *\/\n    .speras-m4-ext-container { font-family: 'Inter', 'Helvetica Neue', Arial, sans-serif; color: #333; line-height: 1.7; max-width: 950px; margin: 0 auto; background: #fafafa; padding: 40px; border-radius: 8px; border: 1px solid #f0f0f0; box-sizing: border-box; }\n    .speras-m4-ext-container h2 { font-size: 30px; font-weight: 900; color: #111; margin-bottom: 15px; line-height: 1.2; text-align: center; }\n    .speras-m4-ext-container h3 { font-size: 22px; font-weight: bold; color: #111; margin-top: 0; border-bottom: 2px solid #eee; padding-bottom: 10px; margin-bottom: 20px; }\n    .speras-m4-ext-container p { font-size: 18px; color: #444; max-width: 800px; margin: 0 auto 15px auto; }\n    .speras-m4-ext-container ul { font-size: 16px; line-height: 1.8; padding-left: 20px; margin-bottom: 0; color: #555; }\n    .speras-m4-ext-container li { margin-bottom: 12px; }\n    \n    \/* 响应式网格布局 *\/\n    .m4-ext-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 30px; text-align: center; }\n    \n    \/* 图片交互 *\/\n    .m4-ext-img { width: 100%; border-radius: 8px; box-shadow: 0 4px 15px rgba(0,0,0,0.05); transition: transform 0.2s; cursor: zoom-in; display: block; margin: 0 auto; }\n    .m4-ext-img:hover { transform: scale(1.02); }\n\n    \/* FAQ 手风琴样式 *\/\n    .m4-ext-faq details { background: #fff; border: 1px solid #e0e0e0; border-radius: 8px; margin-bottom: 15px; padding: 20px; cursor: pointer; transition: all 0.2s ease; box-shadow: 0 4px 15px rgba(0,0,0,0.02); }\n    .m4-ext-faq details:hover { background: #f9f9f9; }\n    .m4-ext-faq summary { font-size: 18px; font-weight: 800; color: #111; outline: none; }\n    .m4-ext-faq details p { margin-top: 15px; margin-bottom: 0; color: #444; padding-top: 15px; border-top: 1px solid #eee; font-size: 16px; line-height: 1.6; }\n\n    \/* ========================================================= *\/\n    \/* 📱 移动端防重叠与行高修复补丁 (真正解决问题的方案) *\/\n    \/* ========================================================= *\/\n    @media screen and (max-width: 850px) {\n        .speras-m4-ext-container { padding: 15px !important; }\n        \n        \/* 强制打散所有网格，变为上下单列 *\/\n        .m4-ext-grid { display: block !important; }\n        .m4-ext-grid \u003e div { display: block !important; width: 100% !important; margin-bottom: 30px !important; }\n\n        \/* 释放文字高度，正常换行，绝不暴力截断单词 *\/\n        .speras-m4-ext-container h2, .speras-m4-ext-container h3, \n        .speras-m4-ext-container p, .speras-m4-ext-container span, .speras-m4-ext-container li,\n        .speras-m4-ext-container a {\n            white-space: normal !important;\n            word-wrap: break-word !important; \/* 仅在单词超长时断行 *\/\n            height: auto !important;\n            max-height: none !important;\n        }\n\n        \/* 🚨 核心修复：强制撑开行高，绝杀上下行文字重叠 *\/\n        .speras-m4-ext-container h2 { font-size: 26px !important; line-height: 1.4 !important; margin-bottom: 15px !important; }\n        .speras-m4-ext-container h3 { font-size: 20px !important; line-height: 1.5 !important; margin-bottom: 15px !important; }\n        .speras-m4-ext-container p, .speras-m4-ext-container li { font-size: 16px !important; line-height: 1.6 !important; }\n    }\n\u003c\/style\u003e\n\u003cdiv class=\"speras-m4-ext-container\"\u003e\n\u003cdiv style=\"text-align: center; margin-bottom: 40px;\"\u003e\n\u003ch2\u003eTB217 Extension Tube: Maximize Your M4 V3\u003c\/h2\u003e\n\u003cp\u003eTransform your compact \u003ca href=\"https:\/\/sperasflashlight.com\/products\/speras-m4-compact-type-c-rechargeable-edc-flashlight-2000lm-700m\" title=\"SPERAS M4 V3 Compact EDC Flashlight\" rel=\"noopener\" target=\"_blank\"\u003e\u003cspan style=\"color: #ff4500;\"\u003e\u003cb\u003e\u003cu\u003eSPERAS M4 V3 Flashlight\u003c\/u\u003e\u003c\/b\u003e\u003c\/span\u003e\u003c\/a\u003e into an outdoor-ready searchlight powerhouse. The \u003cstrong\u003eTB217 extension body\u003c\/strong\u003e allows you to seamlessly swap out the standard 18350 battery for a massive high-capacity 21700 lithium-ion cell, instantly boosting both your peak brightness and overall runtime.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"display: flex; flex-wrap: wrap; gap: 30px; margin-bottom: 40px;\"\u003e\n\u003cdiv style=\"flex: 1 1 100%; background: #fff; border: 1px solid #e0e0e0; padding: 30px; border-radius: 8px; box-shadow: 0 4px 15px rgba(0,0,0,0.02);\"\u003e\n\u003ch3\u003eWhy Upgrade to the TB217 21700 Tube?\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eUnleash Peak Performance:\u003c\/strong\u003e With the higher discharge rate of a 21700 battery, the M4 V3's maximum output jumps to a blinding \u003cstrong\u003e2800 lumens\u003c\/strong\u003e and extends the beam distance to \u003cstrong\u003e740 meters\u003c\/strong\u003e.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExtreme 500-Hour Runtime:\u003c\/strong\u003e Accommodating a 5000mAh 21700 battery drastically increases your efficiency, pushing the maximum ECO mode runtime to an incredible \u003cstrong\u003e500 hours\u003c\/strong\u003e for off-grid survival.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eImproved Ergonomics:\u003c\/strong\u003e The extended body length provides a comfortable, full-hand tactical grip, ideal for night patrols, search and rescue, or use with heavy gloves.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSeamless Integration:\u003c\/strong\u003e Simply unscrew the original short body and thread on the TB217 extension. Machined from the same aerospace-grade 6061 aluminum alloy with Military Type III hard-anodizing for a perfect match.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c!-- Note: Update the image SRCs below with the actual Shopify CDN links for the TB217 tube when available --\u003e\n\u003cdiv class=\"m4-ext-grid\"\u003e\n\u003cdiv\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"margin-top: 50px; margin-bottom: 40px;\"\u003e\n\u003ch3 style=\"text-align: center; border: none; font-size: 24px;\"\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cdiv class=\"m4-ext-faq\"\u003e\n\u003cdetails open=\"\"\u003e\n\u003csummary\u003eWhat is the TB217 Extension Tube used for?\u003c\/summary\u003e\n\u003cp\u003eThe TB217 is a custom-machined accessory designed specifically for the \u003cstrong\u003eSPERAS M4 V3\u003c\/strong\u003e flashlight. It replaces the original short battery tube, allowing the flashlight to be powered by a much larger 21700 lithium-ion battery (like a 5000mAh cell) instead of the standard 18350 battery.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWill this tube make my M4 V3 flashlight brighter?\u003c\/summary\u003e\n\u003cp\u003eYes! Upgrading to a 21700 battery via the TB217 tube unlocks the flashlight's peak potential. The maximum lumen output increases from 2200lm to \u003cstrong\u003e2800 lumens\u003c\/strong\u003e, and the maximum beam throw distance is extended from 700m to \u003cstrong\u003e740 meters\u003c\/strong\u003e.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eHow much does the runtime improve with the 21700 battery?\u003c\/summary\u003e\n\u003cp\u003eThe runtime sees a massive improvement. When equipped with the TB217 tube and a high-capacity 5000mAh 21700 battery, the M4 V3 can run for up to \u003cstrong\u003e500 hours\u003c\/strong\u003e continuously on its lowest ECO setting, making it perfect for extended camping trips or emergency blackouts.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"margin-top: 30px; padding: 25px; background-color: #f9f9f9; border: 1px solid #eaeaea; border-radius: 12px; text-align: center;\"\u003e\n\u003ch3 style=\"font-size: 18px; font-weight: bold; color: #111; margin-bottom: 15px; border: none; padding: 0;\"\u003e📦 30-Day Satisfaction Guarantee\u003c\/h3\u003e\n\u003cp style=\"font-size: 15px; color: #555; line-height: 1.6; margin-bottom: 0;\"\u003eWe stand behind our quality. If you are not completely satisfied with your purchase, you may return it within 30 days of delivery for a full refund or exchange.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e","brand":"SPERAS","offers":[{"title":"Black","offer_id":43694910013617,"sku":"M4 v3 TB217","price":22.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0605\/4549\/9313\/files\/M4_V3_8.png?v=1786073991","url":"https:\/\/sperasflashlight.com\/products\/speras-m4-flashlight-21700-battery-extension-body","provider":"Speras Light","version":"1.0","type":"link"}