7/16 inch x 3/4 inch. Tough under fire. Same key opens all four locks. Suggested Uses: Suitcases, briefcases, golf bags. 1. Steel shackle. 2. Scratch resistant vinyl cover. 3. Made of corrosion resistant materials. Vault: masterlockvault.com - Safely store your combo, key number or confidential data. Limited lifetime warranty. www.masterlock.com. Made to exclusive Master Lock specifications in China.