Standard padlocks may not fit, or may be difficult to use. Ours are slim line, and very heavy duty, specifically designed to work best with our security lock boxes. (Easy to insert, lock and unlock the padlock inside the lock box). Comes with 4 keys. Price includes postage and handling via parcel post (unregistered, approx 3 business days delivery), Australia wide. Express post, and/or registered mail available on request for an additional fee.