Channel nut, long spring. Electro zinc plated. Unistrut's Zinc Coating provides two types of protection: 1) Barrier - protecting the steel substrate from direct contact with the environment. 2) Sacrificial - safeguarding against scratches and cut edges through an anodic sacrificial process. Short Spring channel nuts are specifically designed for 21mm deep channels. The Sprung channel nut versions securely hold themselves in position, while Plain channel nuts need to be pre-mounted on a bolt before insertion. Our Short Spring Channel Nuts are compatible with all 21mm deep sizes of Plain & Slotted Channel and suitable for use in all 21mm Unistrut type Strut Channel systems. They are supplied in a Bright Zinc Plated (BZP) finish for internal applications and are also available in long spring and plain channel nut versions. This product comes with a 10-year warranty.