Yes, it's synthetic - while most dance shoes have a suede or chrome leather sole on them - Bleyers are outsoled with hard non-marking rubber - and traditionally rubber doesn't have much "slideability" - but the Bleyer SpecialSole is different: You can spin on it. You can slide on it. You can swivel on it. And you won't slide all over the place when you rock step. (Great for aerials). Suede on the other hand, becomes slippery and isn't much good for all the hopping and rock stepping of Swing Dancing.
 

Note the SPIN SPOT. Now what do you suppose that's for?

AND YOU DON'T HAVE TO CARRY YOUR SHOES TO THE DANCE IN A LITTLE BAG! You can wear these anywhere, walk in the snow, jump in mud puddles - they don't care...

The Special Sole is not available for sizes 48-50. A similar variant is used. 

The Special Sole as pictured is found on the Rock'n'Roll, Basic Black and the exclusive New Yorker shoes. The Swivel shoe and Suzy Q have a variant of the sole made in a similar synthetic formula.The sole is black on all shoes except the white Swivel, where it is white, and the Brown and White New Yorker, where it is brown.