The nice feature of this design is that the width can be adjusted from the top while the slider is in it's track. It appears similar to what INCRA uses in their hardware.I got 2 of these Aluminum runners for Mitre slots from ebay last year
costed me only US$10 each (free shipment from Germany to Australia)
Spare 3 black plastic washers allow you to fit loose mitre track..
In attached picture top one is bottom with metal washers on both ends - for mitre track with t-slots.
Bottom in picture is top when on mitre track with 3 black replaceable washers to fit loose mitre track.
(sorry I don't have the link anymore since it was 1 year ago). Please search in ebay.
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