The Butterfly Extended is a beautiful pose and advanced pole dance move that requires that you first have a strong basic invert and can do the
Basic Butterfly.
As with learning all inversions and advanced pole moves, you should know all of the
pole dance safety guidelines
and use a spotter and/or a
crash mat.
This move can be learned from the floor first so that you can feel the way your body weight feels being held by your ankle/heel or arch of your foot.
I have seen this trick performed both ways.
Do not use heels at first in this move until you know how to hold your weight with one leg.
Also, the split grip used in this move is the same as used in the butterfly. The closer your hands are together on the pole, the father out you extend the core of your body and the farther out your legs can extend away from the pole.
Here is a simple video clip of the move being performed: