Screw Grommets provide a quick, positive securing of panels or PCBs. As the self tapping screw is engaged, the bottom legs are forced outward eliminating the need for a nut. These go in a square hole that prevents rotation.
These collar spacers are a two piece application; the pin and the retainer. They were designed to capture the PC board. The combination of the mating parts forms a completely enclosed nylon spacer. The use of a binding head type screw is recommended.