Hi Mark. I have done some measurements and have two photos of the frame rails and also a rather clumsy JPEG drawing with the dimensions on. I cannot see a way to load them on to this page so if you know how to do this let me know, or give me an email address instead and I will send on to you. If you don’t want to put your email address on this site then email me separately on waynerr@btinternet.com and I’ll send them over. The distance between the outer edge of the jaws across the frame is 205mm and along the length of the frame is 325mm. The internal width of each jaw is 10mm. Wayne