The narrow, tapered blade of a keyhole saw is ideal for cutting tight-radius curves in a variety of materials. It's also a good choice for making inside cuts in tight quarters. Home Improvement Encyclopedia
A keyhole saw (also called a pad saw, alligator saw, jab saw or drywall saw) is a long, narrow saw used for cutting small, often awkward features in various building materials. There are typically two varieties of keyhole saw: the fixed blade type and retractable blade type.