Utilizing a double circuit linear motion ball bearing system, the load is supported by several lines of balls inside return circuits which infinitely circulate com one side of the retainer to the other. The no-impact nature means there is less stress placed on the joints. It's superior to a free weight machine because it's safer for muscles and joints and can be used without a spotter. Ultrasonically tested, recirculating ball bearings offer. Simply lock the bar into position and add your weights.
Smooth operation is the key.