Abstract: A lock is disclosed for use within an attachment system that connects a ground engaging tool to a bucket lip. The bucket lip has a lug attached thereto, and the ground engaging tool having a recess which receives the lug in use. The lock is disposed, in use, between the lug and the ground engaging tool. The lock has a body, a force applying member and a force receiving member, such that the application of force by the force applying member causes the force receiving member to protrude from a first side of the body and to engage the lug. The present invention involves providing a preferred failure mode for the lock.