The roller parts will help keep your guitar in tune better when bending strings or using a vibrato system.specificationsbridgediameter anchor: 12mmlength anchor: 20mmthread studs: M8diameter studhole in bridge: 6mmspacing studs: 74,0mmstringspacing E-e: 52mmradius: 15"wire retainer: nosaddles notched: n.a.finish: chrome