Durometer – Scale for measuring the hardness of a wheel material.

Load Capacity – The load a caster or wheel will hold. 

Overall Height – The total vertical distance from the floor to the top of the mounting plate, or the base of the stem of the caster.

Raceway – A channel that consist of one or two rows of ball bearings or rollers, which allows a caster to swivel.

Retaining Washer – A washer pressed into the hub ends to retain the bearings.  Sealed version of this washer keeps grease in and debris out of the bearings.

Rig – A caster without a wheel.

Rollability – The ease of starting and maintaining rolling motion.  Rollability is determined by many factors like, durometer of wheel, floor conditions and surfaces, load, and size of wheel and the wheel bearings.

Swivel lead – The distance between the centerline of the kingpin and the centerline of the axle of a swivel caster.  The larger the offset the easier swiveling, but the smaller offset offers greater strength.

Swivel Radius – The horizontal distance from the center of the Kingpin to the edge of the tread of the wheel.

Tread Width – Width of the  wheel tread.