Originally Posted by Salamandrine

The Polar bottles I have fit perfectly. When they are in there is no deformation at all of the bottle. The cage does spread slightly (1 or 2 mm??) when they are inserted or removed. So yeah, they are a bit more grippy than some cages, but that's what you want for rougher roads and fire trails. FWIW it's easy enough that I have no problems pulling the bottle to drink while riding. I didn't bend the King cages - bone stock.

EDIT : Out of curiosity I measured the diameter of the bottle and it is 74mm, same as all my other bottles. The cage is 73mm wide at the opening, so there ya go. I suppose it could be bent open slightly if you prefer an easier fit.