LitterWorks&reg; Permanent Scoopfree&reg; Compatible Litter Tray. Heavy duty, "seamless" plastic design replaces disposable tray refills, pays for itself in a few months. Made in the USA. Single piece, seamless construction made of extra durable ABS plastic. Rounded inside corners make periodic cleaning easier than competition. Includes "nose guard" plastic strip to reduce odors and special cleaning tool Saves $$ over disposable cartrides, pays for itself in 2-3 months!