The Adidas Optifit Stabil squash shoes are quite popular on the men’s professional squash tour. They’ve been used by top-10 players Gregory Gaultier, James Willstrop and Peter Barker, as well as other players. They’re part of the Adidas Stabil line of shoes.
Adidas Stabil Optifit 2012
It looks like Peter Barker plays with this pair (source):
This Optifit “sharp blue” style is worn by Jonathan Kemp:
Adidas Optifit Squash 2011
And Gregory Gaultier seems to favor the white / silver / green pair:
There’s also this red guy:
And there’s even this crazy one, which is called the Adidas Stabil Optifit DHB, and is only worn by squash elves:
Here’s another I found called the Adidas Stabil Optifit FFH, apparently designed in the colors of the French flag:
Squash players go through many pairs of shoes during the year, so if you look at pictures/videos of players you might see them wearing a different style (though they usually stick with one brand, especially if they are sponsored by that company).