how do you go about choosing which condoms to buy? i can take measurements before i go to the shop. they only seem to have a width measurement on them (from what i've seen). i'm not sure where/how that measurement is supposed to be made. also do they vary much? as condoms are made from a stretchable material and are going on to something which changes size, are most regular condoms the same and it's not something to get too deeply into... is it only if the member is extremely unusual in shape and size, that you need look much further into this. also do they need to have a bsi kitemark? or is the ce mark good enough?