These are 1/4″ Nickel Plated Brass Dura-Collars.
Features:
Nickel plated brass construction
Includes:
Two collars
Two 8-32×1/8″ set screws
Requires:
Installation.
5/64″ allen wrench
Technical Specifications:
Length: .250″
Diameter: 1/4″ ID .487 OD