The 22mm round PCB driver has 2 modes(One is highlighted, the other is flashes.)

Voltage boost efficiency: over 95% when when it’s 4V, over 86% when it’s 3V.

Dimension: φ22mm

Reverse connection protection: unique reverse connection protection design, using high current MOS for reverse connection.

Quick start protection: filter capacitors for both input and output

Polarity direction: see pictures

Applications: Laser Pointers, Laser torches, Flashlights and so on

Power supply: recommend 3.7V Single rechargeable lithium battery (16340, 18650, 14500 or 18500 batteries).