The OASIS Bell-Bottle is a rigid water bottle with a round domed top that duplicates hte shape of a bell-jar formwhichit getsitsname. Bell-Bottles fit well on cages available in today's market and come in a variety of gem-like colors to matchplastic habitat pet homes and please everyone. Bell-Bottles are made using breakage-resistant rigid crystal-styrene plastic and hold water well. Complete with color-coordinating cap stainless steel drinking tube containing two stainless steel balls and mounting bracket. 4 ounce size.