Special fastener with a square hole within the round insert base. This fastener is designed to be used as a supportive apparatus to the carriage, elevator, and any other bolt with a square under carriage. The fastener can be used in wood, metal, brick and plastic preventing the bolt from spinning when the nut is tightened. You now can change a hole into a square.  Available sizes 1/2, 3/8, 5/16  &  1/4. The Carriage Secure fastener can prove to be a long term benefit to any small or big project.