Channel nut, long spring. Electro zinc plated. Unistrut's Zinc Coating offers two types of protection. 1) Barrier, The zinc coating protects the steel substrate from direct contact with the environment. 2) Sacrificial, the zinc coating will protect scratches, cut edges, etc. through an anodic sacrifical process. Short Spring channel nuts are designed for use in 21mm deep channels. Sprung channel nut versions will hold themselves in position whereas Plain channel nuts are pre–mounted on any bolt prior to insertion. Our Short Spring Channel Nuts that are compatible with all 21mm deep sizes of Plain & Slotted Channel. Suitable for use in all 21mm Unistrut type Strut Channel systems. Supplied in Bright Zinc Plated (BZP) finish for Internal applications. Also available in long spring and plain channel nut versions. It comes with a warranty of 10 years.