ToolUSA Hide-a-key Rock And Under Car Storage Boxes - Never Be Locked Out Again!: KIT-TA7203 Magnet securely attaches and holds case to any steel surface like bumper, undercarriage, garage etc Rust-proof, rough & weather-resistant ABS of magnetic cases stay securely closed Recessed magnets hold strong - will not let go when vehicle is in motion Key hiding rock measures 3.5 inches - blends into yard Standard key holders measure 3 inches - Large key holders measure 4"