Intended for use with carriers, holding pens or cages, Lixits Small & Toy Breed Dog Water Bottles are easy to install and ideal for small or toy dogs. This small dog water bottle attaches easily and fits most cages, and features a stainless steel drinking tube with a double ball. Attaches easily to cages Keeps water fresh and clean Designed for smaller breeds and puppies Filling Instructions: Water bottles work on a vacuum lock. When bottle is filled and first inverted, press the control ball and let water trickle out until vacuum develops before placing bottle in holder.