20 Series
- Heavily emvossed, formed steel double cup.
- Double row ball bearing raceway construction.
40 Series
- [Cold forged] top plate and base.
- Double row ball bearing swivel raceway construction.
42 Series
- [Cold forged] top plate and yoke base.
- Hardened Raceway.
94 Series
- Shock absorber casters
- Medium to high capacity
- Double Row ball bearing raceway
- Construction for strength
- Heat treated raceway
