Pure Crystal 2.5 L For dogs it is a basic size that covers widely the dogs kept indoors. We adopted a newly designed top funnel (drinking mouth) flowing after water once so that the dog is easy to drink. GEX Pure Crystal Bowl helps you to eradicate these problems! Using a water pump to circulate the water through a unique filter that traps dirt/hair/uneaten food & reduce odour & chemicals, your pets will receive clean, fresh & aerated water all the time.