The Shimano options have a longer tooth on the top sprocket to improve shifting, the lower jockey wheel has a shorter tooth profile to reduce noise and increase efficiency. The unique narrow-wide tooth profile design also allows for better shifting and reduced noise from your drivetrain.
eBay
WUZEI-Nylon Fiber Road Bike Jockey Rear Derailleur Repair Kit, MTB Pulley Wheel, Jockey Wheel, Shimano SRAM X01, XX1, GX, NX, 11
Aliexpress UK
Here is a pair of brand new Nukeproof upgraded derailleur jockey wheels. Both 13 teeth upper and lower. Suitable for Shimano and SRAM derailleurs with this fitment. (Count the teeth on your old one to check) Part no: NUKSH12MJW Please check pictures for all details. Postage included. Cheers, Andy.
eBay
Bike Rear Jockey Pulley Ceramic Bearing Derailleur Jockey Wheel Ultralight MTB Road Bicycle Derailleur Guide Wheel Accessories
Aliexpress UK
Genuine Nukeproof Shimano 12 Speed Jockey Wheels Set. Nukeproof Design. (Upper Pulley 13T / Lower Pulley 13T). Upper Pulley 13T / Lower Pulley 13T. The Shimano options have a longer tooth on the top sprocket to improve shifting, the lower jockey wheel has a shorter tooth profile to reduce noise and increase efficiency.
eBay
Portable Aluminum Alloy Bicycle Jockey Roller 11T Pulley Guide Roller Rear Derailleur 5 Colors MTB Road Bicycle MTB Jockey Wheel
Aliexpress UK
ENLEE Bike Derailleur Jockey Wheel 11T 13T MTB Road Bike Rear Bike Bearing Pulley Jockey Guide Roller Bicycle Derailleur Repair
Aliexpress UK
Stone Bike Rear Derailleur Pulley POM NSK Bearing Jockeys 12T 14T 16T MTB Road Bike Narrow Wide Teeth Jockey Wheel Roller
Aliexpress UK
TOOPRE 11T MTB Rear Derailleur Jockey Wheel Ceramic Bearing Pulley Road Bike Jockey Rear Derailleur Repair Kit
Aliexpress UK
ENLEE Aluminum Alloy Bike Pulley Wheel 10T/12T/14T/16T Ceramic Bearing Rear Derailleur Jockey Wheel rust-proof Bike Guide Wheel
Aliexpress UK
ENLEE Aluminum Alloy Bike Guide Wheel 11T 13T Wear-Resistant Rear Derailleur Jockey Wheel CNC Stable Pulley Wheel Bike Accessory
Aliexpress UK