This is a set screw lock collar. It is for a 0.75 or 3/4 inch shaft. They are steel and zinc coated. Perfect for keeping your shafts or bearings in place.
Shaft Collars (sometimes called lock collars) are easy to install; the collar provides an easy way to keep your shaft from sliding or your flanged bearing from coming out.
ABS Plastic Multipurpose Enclosures w/ Card Guides 1591 Series
Flame Retardant, General Purpose, Flanged Lid or Bottom
pack of 2, 12mm Hex wheel adapter for 6mm shaft
light-weight aluminum shaft adapters convert a typical motor output shaft into a 12 mm hex shaft that is compatible with many RC wheels.