I ordered 12mm x 30mm. It was mentioned in the rubbing strake thread that something a bit thicker – around 19mm – might be preferable, but the 12mm was certainly easy enough to bend and fit to the shape of the boat and so far I’m quite happy with them. The material was not supplied as a rounded profile, I just rounded off the top outer edge slightly with sandpaper. Difficult to advise whether you should fit it yourself or not but in a nutshell I cut a 45deg angle on the f’wd end to fair it into the bow, lined up the material with the gunwhale, drilled and countersunk, and then attached with self tappers, sealing the holes into the bouyancy tanks. I treated them before and after fitting with teak oil. Like everything, other people will have done it in different ways, but I just tried just to keep it as simple as possible. Good luck!