P1 jumper on the Legit ProxPro’s designate if it is on a metal wall or a non-metal wall.
Yeah it is actually part of the Weigand response that is generated on each read
The only reason i know this is i purchased a couple proxpro’s and an R90 in hopes to strip this data out on read and harvest its high powered antenna for our Injector Reader that ive been testing. Spoiler: I cant.