Powerflex

PFF5-4601 & PFF5-5601 fit brackets with a 66mm bore
PFF5-4601-60 & PFF5-5601-60 fit brackets with a 60mm bore , usually found on earlier models.
PFF5-5601G & PFF5-5601G-60 give an additional +0.5° Caster (gives standard caster on Z4M)
For the Z4M use PFF5-5601G to achieve the standard caster, other front arm bushes will reduce the caster.
PFR5-4610 & 4611 are complete replacement bushes, for inserts use PFR5-4613 & 4614 (inserts fit into the voiding of the original bush)
PFR5-4621 fits Z4M models only
PFR5-4609-22.5 Fits Z4M models only
PFR5-5630-10 fits cars with standard or aftermarket rear shock absorber with a 10mm pin, PFR5-5630-12 fits cars with aftermarket rear shock absorbers with a 12mm pin