Bushing increases the accuracy of your 1911 by reducing the loose fit of the factory bushing to the slide and barrel. Some fitting will be required. Steel.
Drop-In bushings are designed to fit in a 1911 slide with standard dimensions at bushing opening. Oversize bushings have extra material on outside diameter and will require fitting to insert into busing opening of slide.
The spherical bushing is designed to increase accuracy and reliability by maintaining perfect alignment from barrel to slide by a unique system using a spherical ring. If the spherical bushing is disassembled, re-insert the ring in the horizontal cut and rotate to seat. Ensure that there is linear movement in the assembly. Lateral (axial) movement should be non-existent and is best checked in your gun when in the locked position to avoid misinterpreting axial movement with pivot.
Ring to Barrel Fit: Simply measure barrel at the muzzle and ensure that the number on the ring is .001 of an inch larger than the outside diameter (i.e. a .582 barrel O.D. should be fitted to a .583 ring). For those using an undersized ring (.575) a competent gunsmith should exercise care in not turning the barrel more than .001 under the size of the ring.