1018 Steel T-Slot Nut, Black Oxide Finish, 5/16"-18 Threads, 1/2" Height, 1/2" Slot Depth, Made in US (Pack of 5) Go to amazon.com Related posts Best t-nuts 5/16 FeatureMaterial is case hardened 1018 steel with black oxide finish5/16"-18 Thread1/2" Table slot7/8" Base sizeMeasures 1/2" width by 7/8" height DescriptionMaterial is case hardened 1018 steel with black oxide finish. 5/16"-18 Thread. 1/2" Table slot. 7/8" Base size. Measures 1/2" width by 7/8" height.