This simple accessory prevents your tape measure from slipping off the corner while measuring diagonals. The 90 inside corner securely straddles any outside corner, and rotates 360 to accomodate any rectangular object. It attaches easily to your tape with a single, powerful rare earth magnet. Use it while assembling drawers for a perfectly square batch. Also great for cases, frames and more. Slot for tape hook measures 1-1/8″ wide. Made of durable plastic.