Safe, portable design. Compact size of 5 1/4"w x 1 3/4"l x 2 3/8" h. Ideal for home, office or briefcase. Fully enclosed blades protect fingers. Automatically activates when envelope is inserted. Uses four AA batteries (sold separately). Blade Type: Concealed; Blade Material: Steel; Length: 1.75"; Height: 2.38".