ah, I see! That makes sense. Well, Ipad's collar is *very* thin and very wide - Foggy bought it so Matt could wear it under his shirt invisibly. They'd see it if they made him change out of his clothes and into auction house apparel, though. It doesn't have a buckles so much as more a lock like you'd find on a jewellery necklace (it's a collar for female slaves, actually). It also has his identity chip embedded in the front.
This Matt hates regular collars like nothing else, though, so I think him being collared in the auction house would be the worst.