Electronic sensor knows when your had is nearby and you never have to touch the unit - the top magically glides open - you drop your trash in and step away and the top glides smoothly down and closes without a sound. The unit is perfectly sized for my apartment and keeps my dog out of the trash. It can sit out in the open but not look like a yukky open top garbage pail. This unit takes a 13 gallon trash bag and includes a nice ring that tucks the bag down inside for a terrific clean look, It takes D cell batteries (x4) or you can buy a plug in adapter separately (it doesn't come with the can tho so plan on using batteries or paying separately for the transformer (manufacturer approved transformer only.) It does occasionally open when you walk by but it is silent so it isn;t a big deal.