Tbest 11T Jockey Wheel Bike Rear Derailleur Pulley, 2pcs Aluminum Alloy 11T CNC MTB Road Mountain Bike Derailleur Jockey Wheels Derailleur Pulley Guide Bearing for Bicycle - Black/Red/Golden/Silver

Bought these, just a punt, not that expensive. The bearings seem good, and the product is well anodised. But note the external alu covers sit a bit to wide for shimano road. so you can't get the bolts full tight in your rear mech. i think the external plates just need machining a bit closer. i was trying these on 9150 rear mech. might be ok on an older shimano mech.

Really really good, fits my 9 speed XT Deore with no problems. Its firmed up the gear changing.