By removing the outer rim, you can lift up the sieve, sifting the waste from the litter. With the Alexandria Cat Litter Tray, you can just toss the waste straight from the sieve into the bin, without using a litter scoop, thus it is more hygienic and clean. The double tray system allows you to interchange the litter trays for cleaning and it makes the litter removal process much more easy and convenient. The tray and rim are connected with Easy Click clasps. It works with traditional clay, clumping and silica gel litters.