The pulley wheels are the fastest spinning bearings on your bike. An upgrade to ceramic bearing therefore is the most effective upgrade. C-Bear ceramic pulley can be used both for road, cyclocross and MTB.

Full Ceramic Pulley Shimano Sram|Bi-cycle bottom bracket with ceramic bearings|c-bear.com Pulley Full Ceramic

Shimano-Sram 10/11sp
Sram  AXS 12 speed - road
Campagnolo  11 speed 
Campagnolo  12 speed 
For Road/Race use Only.
Pulley - Titanium |Bi-cycle bottom bracket with ceramic bearings|c-bear.com Pulley - Titanium

Shimano-Sram 10/11 speed
Campagnolo 11 speed

With full ceramic bearings, click here
Pulley Campagnolo|Bi-cycle bottom bracket with ceramic bearings|c-bear.com Pulley Campagnolo

11 Speed  (picture here)
12 Speed
Please select options available from drop down list below.
Available in both full and hybrid ceramic bearings
Pulley Shimano-Sram|Bi-cycle bottom bracket with ceramic bearings|c-bear.com Pulley Shimano-Sram

10/11 Speed:

Aluminium
Carbon
Delrin

With full ceramic bearings, click here
And C-bear OCM (original cage max) click here
Pulley - XX1 Sram|bi-cycle ceramic bearing|c-bear.com Pulley - XX1 Sram

Sram 11 Speed
XX1
XO1
Force CX1
Force 1
Rival 1
Apex 1

 
Pulley - Sram Eagle 12 Speed|bi-cycle ceramic bearing|c-bear.com Pulley - Sram Eagle 12 Speed

XX1 Eagle
XO1 Eagle
GX Eagle
NX Eagle
SX Eagle
 
Pulley wheels OCM (Original Cage Max)|bi-cycle ceramic bearing|c-bear.com Pulley OCM (Original Cage Max)

Shimano:
Dura Ace R9100, R9150 Di2 
Ultegra R8000, R8050 Di2 
GRX 
XTR M9000
XT M8000
SLX M7000
105 R7000

SRAM AXS Road 12 speed :
Force
Red

SRAM AXS MTB 12 speed :
https://www.c-bear.com/en/products/pulley-sram-eagle-12-speed