North Shore Commercial Door has the Genie 24121C05.S Hex Nut for Screw Drive Operators. This particular nut is in used in tandem with the Header Bracket and Rail Strap. The Rail Strap has a built in fastener that fits through a pre-drilled hole in the header bracket. The nut then secures the Rail Strap and Header bracket together, stabilizing the Rail Assembly for the opener.
This fastener is compatible with Professional Line Models: Excelerator Pro99, CMD9900
Retail Line Models: H8000, ISD990, ISD995, ISD1000, QuietLift 4560