This massive 4" Crayford was used on APM's refractors before the anodized CNC TMB rack and pinions arrived. It has a 5.940" diameter OD shoulder that slips into your mounting plate, tube or adaptor (overall focuser body diameter 6.32", height 5.4", in-travel 1.2"), with a V-groove that could allow rotation at the next assembly.
The knobs are massive knurled aluminum 1.5" diameter, an adjustable-tension knob can lockup the movement. Condition is quite good, the finish is black and aluminum, includes a 4" to 2" compression ring adapter with brass hardware. Several standard tapped holes in the body allow for various finder-bracket configurations.
The roller works against a replaceable synthetic flat, unusual in a crayford in that the actual machined-flat compression surface will never develop wear grooves from the roller, and the feel can be adjusted by replacing the replaceable element if desired. I will include spare bearings, although it would be difficult to overload this beast. Minor scoring of the drawube seen in photo. It is not as smooth as the other top-notch machinery above, but at 1/3 the cost and no waiting, I think my price is reasonable. UPDATED: travel is 4.4".
$295 + $20 shipping in CONUS, paypal encouraged.