I have Ali frame any. idea were I can get proper fixings from it has 2 channels to slide on

I got mine from Flatlands Engineering for my Manx type screen! Fairly easy to make your own though!👍

http://www.flatlandsengineering.co.uk/fle/parts/fle_BK22.jpg

I also used flatlands "hidden" brackets and made sure I drilled the mounting holes undersize slightly. Studs are 8mm.. Industry standard hole for 8mm stud is 8.5mm. I went 7.5.

However, after contacting ManxDave re- right way round for the Manx frame he told me he used Gutter bolts. I think he is referring to what I call "roofing bolts" which have a square section directly under the domed head. I was impressed with this as it`s a simple, very cheap solution.

No, just regular M8 roofing bolts, drill slightly undersize so that you can screw them into the fibreglass, slide the screen over then tighten plain hex nuts over flat and spring washers from the underside. It's not moved in 19 yrs.