Made of durable clear plastic with a floating duck inserted as a friendly refill reminder * Stainless steel spring-loaded dripless sipper * Snap-lock Bottle Bracket with the convenient E-Z twist attachment knob allow for effortless bottle removal and refilling * Easily adapts for use either inside or on the outside of the cage * Small 4-ounce size is ideal for the tiniest critters like mice, dwarf hamsters and small gerbils