If Colin Oates was up against a particularly strong or flexible opponent, they would sometimes be able to brace their leg high up and prevent his Sangaku arm tie roll. In this situation he would use his reverse variation.
As Oates secures the tie off, the partner manages to get his foot high up the mat, so much so that he’s even able to prevent the Sangaku variation of the roll.
By spinning down to the bottom half of the body Oates then changes the angle of attack.
He reaches under the outstretched leg, turning the partner in towards him.
He now has their hips in the right orientation, so it’s easy to secure the hold.
However, if your opponent is able to kill the momentum when turning, there is a risk of them escaping. So the movement must be quick and under control, as you spin the partner onto their back and into Osaekomi.