A metre

This is my "M2" extention tube. All metal and strong enough to carry my 1980's 300mm f4 lens on, all day - changing its focus range from 4m - infinity, down to 3m - 4m.
No loss of quality, and lets me get close enough to friendly birds and animals for the shots I like.    My secret weapon to avoid paying a fortune for the new 300 :-)