This is a stainless steel precision washer for dual-bearing V-wheels and idler wheels. It is nominally 1.00 mm thick, 5.00 mm inner diameter, 7.70 mm outer diameter (actual measurements 1.01 mm, 5.05 mm, 7.72 mm, with less than 0.01 mm variation between samples). In addition to the increased precision, these have a major advantage over our old shim washers (and over those from Inventables, which are 10 mm outer diameter): they can not touch the bearing shields, because they are no wider than the inner race of the bearing. This will reduce the chance of problems caused by shields that aren’t recessed enough, and eliminate one source of frustration when assembling your eShapeoko.
Please note that our idler wheel kits and V-wheel shells already include these shim washers.