The Doggie Dooley Model 3800 is larger than Model 3500 and is pyramid-shaped. The Doggie Dooley 3800 Durable plastic parts are stronger and much easier to assemble, and will not corrode or rust. The Doggie Dooley 3800 has a Unique open-bottom system with no need for separate overflow device. The The Doggie Dooley 3800 provides safe disposal of pet waste and control of odors. Includes handy foot-operated lid and comes with an expansion kit to increase capacity. 24-1/2" deep x 18-1/4" wide. Scoop included.