Stainless steel makes straight edges a snap.
In my job I do a bit of drafting. wooden and Plastic rules just do not hold up to constant use. The get chips or bends in the metal guide. That make work look unprofessional. This stainless steel one has held up fantastically. The cork backing keeps it from sliding while trying to use. And it’s sturdy enough where I can tell it will stand up to years of use.