Description: Takes 1/2/3/4 standard size 18650 batteries side by side to form a compact battery of 3.7V rechargeables Keep your batteries organized and protected Specification: Material:ABS Color:Black Size: Approx.78mm * 21mm/40mm/60mm/80mm * 21.5mm (excluding the lead part) Weight:Approx.10g/15g/20g/25g Pin: length Approx.3.5mm, longitudinal spacing:Approx.72.5mm (both edge-to-edge spacing) Mounting holes: Aperture Approx.3mm, longitudinal spacing Approx.55mm (Pitch is the distance center to center of aperture) Instructions for use: 1 single 18650 battery use 3.7V.                       2 18650 battery, in parallel or in series to achieve 3.7-7.4V                       3 18650 battery, in parallel or in series to achieve 3.7-11.1V                       4 18650 battery, in parallel or in series to achieve 3.7-14.8V Attention: Size may be slight inaccuracy due to different batches of the products, or hand measurement; Color may be little different due to monitors. Please take real product as standard, thanks for your understanding!    Package Included: 50* 18650 Battery Storage Box Holder with Pin