Hello I would strongly recommend a 4x mate get a Altair 4x that’s your best bet also do you understand the gases levels etc and calibration on the device ie bump stumps etc ?
I have been on trips before dropped in between a 2ft wall and a 2ft wall in open air with the addit at my feet and it plummeted to 14.1% o2! That makes you feel horrible it’s a very dangerous game not impossible by all means just learn everything before you attempt places that are dangerous as a single mistake could be your last
Ill have to have a look around and see what sort of prices i would be looking at, obviously i know if i spend peanuts i get peanuts! No im not to knowledgeable i.e bump stumps, i know they need to be calibrated every few months, but my information regarding the monitors themselves is relatively low.