Tri-Groove Tamper Proof Security Nuts Zamak 5 Zinc Anti-Theft 1/4"-20 Tri-Groove Nuts, are suitable for providing tamper-resistant fastening for a wide variety of applications. Tri-groove nuts have been used extensively in correctional institutions, hospitals, universities, public places, and retail stores to secure a variety of products including inmate furniture, scaffolding, electrical and electronic equipment, computers and related equipment, traffic signs, park benches, outdoor play equipment, and consumer product displays. Tri-groove nuts feature a conical design that prevents unauthorized removal. It has 3 indented slots for installation and removal with a proprietary tool.