Very tidy and accurate ( as would be expected at this budget ) came well packaged, initial tests seem to show its ideal size for marking out. I have never been a punter for massively long squares but the 40cm is a good in between.
This seems like a great, and much needed upgrade to the cams which constantly came loose. Haven't cut with it yet but putting a large accurate square against it shows that the rail square is still a perfect 90° to the rail. The drilling jig is a good idea and the drill/tap bit works well. The screws are very soft however and the small internal hex rounded off with very little pressure applied, so I swapped them out for good quality torx screws. Also the card that comes with it that has a 2 x QR codes to take you to instructions takes you to instructions for the rail square mark III not the clasp instillation. I was unable to find either written or video instruction on how to install it depsite 2 QR codes on the card which are meant to direct you to them. It's expensive for what it is but a much better solution than the cams were so hopefully will be worth it in the long run. Overall happy with the product. Just needs some improvements regarding the screws and instructions.