[quote=rider89]
"jw 1111" wrote in message
...[color=blue]
Hi, i want to fix an arial to a wall. it comes with a metal bracket
through which to use screws to put into plastic rawlplugs in the wall.

since i will need to take it down again in a few years; which screws
should i use that are least likely to rust?

I live close to the sea - it is very humid and saline.
I have found that the best external fixings are any form of good quality stainless steel bolts, be they recessed-head with Allen Key hole or hexagonal head, or posi-drive - it don't matter. Use 8mm thread and screw them into plastic plugs that require a 10mm hole. I buy my plugs from the German manufacturer Wurth as also the bolts. In 8mm the fit is exact which is not the case with other sizes.
Be sure to put some Lithium grease or Vaseline on the bolt, and do drill the wall to the exact size because a bolt has no taper and does not expand the plug to fit the hole.
I have been using this system for many years and have repeatedly found that it is possible to dismount anything, even door frames for painting, with the greatest of ease after years and years of the acutest weathering. The bolts never rust in the plastic and with grease and so do not expand and rupture the masonary. Very occassionally a plastic plug gets mangled by over tightening but that is really quite easy to replace. If the bracket is of steel put a stainless washer behind it so that it does not directly touch the wall. If your walls are limestone it is even better to put a simple homemade washer of bitumen roofing membrane or something similar but in U.K. you are probably fixing on brick which is pretty inert.
regards, Tghattaq