beam clamp 1.Universal malleable iron beam clmap 2.Size range:1/4-20,3/8-163surface finish:black,electro-z Light Duty Beam Clamp ... ,Spring Steel Clamp 1.universal malleable iron beam clmap 2.size range:1/4-20 ... /4", Additionally, they have sharp teeth that bite into beam surfaces to protect against slippage Light Duty Beam Clamp,Spring Steel Clamp