Prakash 3 Inch Medium Duty 2 pcs Swivel & 2 pcs Safety Break Swivel Type ESD Caster Wheel
Caster wheels are attached on the base of device moving equipment and bring about mobility of those objects. They enable movement of heavy objects with less force being applied 

Electrostatic dissipative (ESD) caster wheels are designed to prevent the buildup of static electricity and protect sensitive electronic equipment from electrostatic discharge.