Casabella Cut 'n Slice Pizza Cutter, Dark Grey/Red To wash blades: Push button, slide blade and lock in place, while locked in place, push button again to carefully remove blade To replace blades: line up the long side of gray tab on the back of the blade and slide into the slot on the body and lock in place Blades are very sharp, use caution when cleaning Push button blade slides down and locks for cutting pizza and doubles as an herb mincer when both blades are used Measures 4-Inch x 4-Inch and is ergonomically designed to be held comfortably in your hand