Cartridge mount screws - stainless steel

I need longer mount screws to mount my cartridge, can i use plain steel screws or must i use stainless steel screws . I am having a hard time finding small stainless srews, 20 mm long locally.
You really don't want any any ferrous metal near your cartridge. It will change the flux pattern of your magnet. Have you tried any of your local hobby supply houses, or Ace Hardware for stainless, brass, plastic or alloy? Here's a link to a mounting kit:( You'd better ask what length he supplys as most mounting screws are 3/8" or less. If you have a McMaster-Carr catalog available to you, you could no doubt find some in there as well.
Tshulba i have found brass is the best for anything to do with audio. Try getting brass screws.
Mapleshade also strongly recommends brass.
Thanks guys i have tried a local hobby shop and one bolt supply and they have shorter stainless but not 20mm. I may have to machine up my own out of brass once i find the proper size die to cut the threads.I found plain steel screws at Radio Shack but it looks like i can't use them.
McMaster-Carr or Turntable Basics
Here is one option. 2.5mm x 20mm stainless socket head cap screw. 12.59 per pack of 50 from McMaster-Carr. Have enough to hand out to friends!

Punch in this part number:

Thanks everyone for your replies.
Is 2.5 -20mm the right size for Shelter 501 MKII?
McMaster-Carr does not have metric sizes brass screws.
Any other sources fro brass?
They seem to be quite difficult to find. You might try asking Mapleshade.
I was not able to locate stainless or brass screws today at least not 20 mm length only shorter ones, they told me they weren't available from the supplier. I purchased a die and made my own brass screws on the lathe , took about .5 hr.
Mounted up the ZYX Airy 3 on the Graham Phantom with the spacer they provide now i have to re-adjust everything.
I had to install the spacer under the cartridge cause my VTA was as low as i could go and i needed to lower it more.
Hi ; If you want to go over the edge Elusivedisc dot com has carbon fiber screws they look great until I saw the price check em out
$199 for two screws- I'm definetely going to pass.
This is one of the most rediculously priced items I've encountered lately.
For $199 i will have to try making some carbon fiber bolts. I have machined carbon fiber rods down to size so i will have to try threading it now.
So, what's the right size? 2.5 mm? Elusivedisc carbon fiber Shelter screws are 2 mm.
Just an update- Mapleshade sells brass mounting screws in 2.5x16 mm size with nuts.
I ordered two pairs, should be "under $5 per pair", I've been told.
They also recommend Nanomount system, which you can see on the Mapleshade website, which should "drastically improve cartridge performance".
Anyone tried Nanomount system yet?
Maril555 i have been using Nanomount and Lp Coupling systems with my Aries Three. Both are a real step up for better sound from your lps improved detail, air, clarity. I will be selling the coupling system and Aries as i have moved in another direction turntable wise if you are interested.