Chinese made J-caged bearings. These are the best EZO style / J-Caged bearings I could source at a reasonable price.  Whilst EZO are nice they're 3 times more expensive.

Most bearings are 2.5mm in height, these are 3mm.  J-cage bearings generally offer the strongest performance for high speed applications.  Inside the bearing is a 2-piece steel ribbon, the cover side and the finger side.  Inside the ribbon are the ball bearings, 6 of them.   Each bearing also contains a small amount of grease.

I tested these on an E&C gearbox.  Fitment was perfect.  Even the spur gear on the selector plate fitted without any modification.  On other gearboxes you may need to cut away or sand parts of the selector plate.  I conducted 2 build tests; M140 full stroke and DSG.  Both builds had 2000 BB's through each, bearings held up without any problems.

Please note that on some gearboxes you may need to modify / trim parts of the selector plate or other parts, do not purchase this product unless you have the necessary skills to install.

Updates:
1. After 30,000 cycles with springs ranging from M100 to M140 the bearings are still in perfect working order.
2. March 2021, still going strong with around 60,000 cycles.
3. Feb 2023, still going strong, now after 300,000 cycles.

Material: Stainless Steel
Inside Diameter: 3.00mm
Outside Diameter: 8.00mm
Width: 3.00mm
Flange O.D: 9.5mm
Flange Width: 0.7mm