Designed specifically for the blades displayed in the link below. You get 15 for $5 which is an insane deal. I carry this with me every day and it comes in handy very often. It's the perfect size for cutting paper, opening boxes, cutting tape, etc. It also comes with a protective case that can be used to attach it to a keychain and also acts as a secondary failsafe to prevent the blade from opening in your pocket.