The 7/8" Lap / Stitch screw is designed to be installed on the lap of your metal roofing and siding panels. This screw is commonly utilized for low slope commercial panels like PBR-Panel, or Box-Rib panel where the rib has a wide, flat surface so the screw can get a good seal. The 7/8" Lap / Stitch screw "stitches" the lapped panel ribs together to prevent separation and prevents siphoning. 
 
Flat-Top lap/stitch fasteners combine under-cut hex washer heads with EPDM cut-tubular sealing washers. They are a superior and cost-effective alternative to standard fasteners with metal back washers.
 
One-piece design eliminates damage to painted washer surface and eliminates dissimilar metal washer materials
Flat on top stabilizes socket during installation
Higher hex provides positive socket engagement
Special undercut entraps sealing washer, even when driven at extreme angles
Assembled with an EPDM Cut Tubular Washer
 
Designed for use where panels lap over one another.