Thankyou all for your replies

Now at least I won't appear slow on the uptake when I go to the shop to choose (well no more slow than usual!!!)

That is the great thing about this forum. There is such a wealth of experience here and yet it feels really safe to ask the most rudimentary of questions without the fear of being considered inadequate. Long may it continue

Now if anyone ever needs information on rodent breeding.......well actually I know nothing about that either

Thanks again
Tony