The Urchin side lock is an innovative approach to solving two common problems, providing a convenient way to lock a zipper mechanism closed and also to ensure that a bag cannot easily be stolen. The Urchin side lock ensures that once closed, the zipper is securely locked in place - a metal loop attached to the zipper is placed over a loop attached to the bag and a strap is passed through, therefore ensuring that the zip cannot be opened. The strap has a combination lock which prevents removal. This strap can also be placed around an object, providing two layers of security.