1. Function: digital display with power, detachable, welding-free, with anti-reverse connection protection, can charge 21 18650 flat-head batteries, when the built-in battery can be used as a power bank, the normal version requires a charging cable, wireless fast charging The version does not require a charging cable and can be quickly. 2. Hand-made DIY mobile power kit, self-configured mobile power, larger battery capacity and more , can better solve your charging problem. 3. Suitable for people with greater charging needs, equipped with 3 charging interface types, for Micro, for ,for Type-C can charge the charging box. 4. With power display, let you know the remaining power anytime and anywhere, and better charge your mobile phone or other devices. 5. Comes with a lanyard, which is more convenient to carry, allowing you to take it wherever you go. Model: T21 series with light Battery: 18650 type flat head battery x 21 (free welding) Size: Thickness 62mm Width 84mm Length 170mm (internal dimensions remove a spring: thickness 55mm width 74mm length 129mm) Parameter: T21-PD with light: output/input maximum power: 5V-3A 9V-2A 12V-1.5A Precautions: 1. The battery cannot be used if its outer skin is damaged. 2. Pointed batteries cannot be used, only flat batteries can be used. 3. The positive and negative poles need to be placed and used correctly. 4. Do not use or store in a high temperature environment. Colour:black Material: ABS Package Contents: 4x 18650 Power Bank Case(Batteries not included) Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.