>It is not a spacer for the legs to butt against. It is, in >fact, a low angle adapter. > >This is how it is intended to be used: Remove the low angle >adapter from the bottom of the center column. Remove the >center column from the tripod. Invert the low angle adapter >and slip it into the top of the tripod where the center column >was. Tighten it down with the same knob used to tighten the >center column. Mount a tripod head on the 3/8 inch stud >protruding from the low angle adapter. You now have a quite >solid support that will allow you to use your tripod at a very >low angle. With the center column removed and the adapter in >place, you can now splay the legs out to 43, 73, or 90 degrees >(flat on the ground) if you like. > >I did it many times with my 3001 for macro work before I gave >the tripod to one of my kids.
Fair enough, it's not 'just' a spacer - however, the only reason it's triangular is so it can fit neatly between the folded legs (where it acts as a spacer) 8>)