Mark, Greenie's glides are designed to fit only one way, the right way, that is with the words back writen on the glide facing you. They have no memory so if you heat it up in hot water and sqeeze it back together it will fit snugley back on your wand. A little tip if you file a groove in one side of the spray shield on your wand the glide will slide nicely alone the lips of the wand without damageing the glide thus making it easer to remove to clean
I use two small pieces of blue tack at each end of my glide to seal it to the wand this stops any air sucking through the ends of the glide.
Some will say it restricts the air flow but I have found the carpets dry far better