Dave, I have to agree, the tool method of isolating the gas was a safer method in M2 but was removed as requested by event organisers. I am in the process of moving the gas bottle in M2XT and will re-introduce the tool method for me but still allow the option for those marshalls who want to put their hands inside to turn off the bottle. I cant remebed what size nut I put on the regulator but it was probably a M10 so a 17mm socket on a Tee bar should do the job nicely. Standardising on a size would be the way to go if the powers that be would consider the option.