agian not really motorhome related but ive bought a new regulator for my mig welder, fitting some new seats to the van and need to alter the seat bases to accept the new seats, in my ignorance i thought that there was ony one size regulator for 10 litre gas bottles.so my regulator came this morning and it wont fit it very nearly fits but wont is there more than one size regulator is there anybody on here thats knows or am i being stupid .thanks in advance