There are two versions of the led collar -- USB Charging Version Charging once the light gets weaker will help to improve the service life of the battery
Other version has a Button Battery which can be replaced when needed. CR2016 Button battery x 2 pcs Please choose the version you want.
Specifications : Width Neck Circumference
XS 2.0 cm 28 - 40 cm/11 -15 inch
S 2.5 cm 35 - 43 cm/13 -16 inch
M 2.5 cm 40 - 48 cm/16 - 18 inch
L 2.5 cm 45 - 52 cm/18 - 20 inch
XL 2.5 cm 52 - 60 cm/20 - 23 inch
Feature: Three flash Mode First Click_Quick Flash Second Click_Slow Flash Third Click_Steady Light