Inexpensive plastic collar. The goal was to earn a living that wasn't covered by a metal detector. Success.Update: After wearing them a lot, I've unfortunately noticed that they warp a bit. If I could recommend an improvement for the manufacturer it would be to increase the thickness of the material to make it less flexible. However, they are certainly thicker than the cheap ones that you get "for free" with the new shirts. Still satisfied, but I'm moving the rating to four instead of five stars.