These 3" casters are great for mobilizing machines or fixtures in the shop. Rubber tires are smooth and quiet, and offer plenty of traction for an effective braking system. Both locking swivel models have a built-in locking lever. One has 1-1/4" long mounting stud with standard metric thread, 12mm x 1.75 pitch; fits 1/2" hole; the other a 2-1/2" square mounting plate. Fixed caster's mounting plate is 2-3/4" x 2-3/8". 150 lb. load capacity.