The Brockhage Clear Standard Pin Practice Padlock will help you practice your lock picking skills because you get a view into how a lock with standard pins functions. You can see all the moving parts when you insert the key into the lock and open it. This is the perfect training tool for a locksmith. The housing is high-quality clear plastic with sturdy metal locking mechanism. Two keys are included and it is 3 4/5”x2 2/5”.