open combination lock

It means the lock’s three-digit code can be changed by the user. Product instructions typically describe an easy reset process — set the dials to the current code, use the reset mechanism (button or pin), choose a new three-digit code, and save it according to the manufacturer’s steps.

Typical shackle diameters range from about 3 mm to 7 mm. Shackle lengths commonly run from roughly 19 mm up to about 38 mm, with smaller/shorter shackles used for luggage and longer/thicker ones for lockers.

Most of the locks use a three-digit combination (described as “three-digit” or “3-digit” in product details).

Listings commonly cite pin-tumbler locking mechanisms, anti-shim technology, and hardened steel shackles as key security features.

Review summaries report that most users find these locks open and close reliably for gym and locker use. Reviewers frequently praise simple dial operation, easy setup, and the convenience of preset or easy-to-remember combinations.