Collar Length (can be adjusted by pulling the LED fibers through the adjustment buckle): 
X-X-Small: Min. 8.6" and Max. 11.4"
X-Small: Min. 9" and Max. 13.7" 
Small: Min. 13" and Max. 17" 
Medium: Min. 16" and Max. 20" 
Large: Min. 19" and Max. 24"
X-Large: Min. 21.6" and Max. 27.5"

THIS WILL SAVE YOUR DOG'S LIFE - Vehicles will see your dog well in advance with this bright collar - ALL THE TIME.

USER-FRIENDLY, COMFORTABLE AND FULLY ADJUSTABLE - Change the light between steady mode, rapid flashing or slow flashing with just 1 click. Thanks to the easy-to-use clips the LED Dog Collar is no hassle to put on.

USB RECHARGEABLE BATTERY, LIGHTWEIGHT, STURDY & DURABLE MATERIALS - The USB rechargeable battery (cable included) gives 5 hours of illumination per 1-hour charge. A charge that will last multiple walks. No hassle with replacing batteries and no extra costs. On top of that, it's well-constructed and sturdily built. A durable design that will last a lifetime!