Disclosed are various exemplary embodiments of a lock for a ground engaging tool. The lock may include a head portion and a C-shaped portion extending from the head portion. The C-shaped portion may define a lock slot for receiving a portion of a support member to be locked with the ground engaging tool. The C-shaped portion may also include an outer surface configured to be rotatably received in an inner surface of a retainer bushing. At least a portion of the head portion and the C-shaped portion may include a surface coated with a friction-reducing material.