A stop block to fit into a T-Track measuring 3/4" by 5/16" or 19 mm by 8 mm, or it can be used with the T-Track insert found in the link below or you can use it with T-Bolts. The holes measure 7mm so you can use ¼" hardware for your track. It has an attempt at a micro adjustment, there are modeled M6x1 hardware but I would recommend using metal hardware - your choice. 

The link to the T-Track insert:

[https://makerworld.com/en/models/944096#profileId-910354](https://makerworld.com/en/models/944096#profileId-910354)