READ CAREFULLY -- These slides were installed about a year ago in our kitchen. They are 21" undermount, full extension with a rating up to 100lbs. They are supposed to be self closing, but occasionally they stick out about a 1/4" and must be pushed to be fully shut. I got tired of doing that and Richelieu says that these models have that issue, so I replaced them with Blum slides. If you don't care about the self closing feature, you might be able to defeat it and just close them manually. They sell for about $60/set so this is a $1000 savings from new! All 21 must be purchased. Full details at website link below.