Chicago Model 1610 watch band style flexible link neck collar. Excellent workmanship and finish. Constructed of nickel plated brass. Includes 3/4 inch steel ring at front. 2 keys stamped Chicago Handcuff included. Available in small (inside perimeter 14.5"), Medium (inside perimeter 16"), and large (inside perimeter 17.5").
Heavy and comfortable, but spike in the rear is unnecessary, June 16, 2017 By Anonymous (CHARLOTTE, NC)
This collar feels great and is very secure, but the pointed end of the darby-style lock is much longer than necessary or comfortable. If adjusted to anything less than the tightest position, it creates a pinch zone on the side of the back of your neck. The chrome plating will deteriorate with even occasional wear, and I recommend hitting it with WD40 when you get a chance.
I once had a problem with the locking mechanism not releasing after screwing in the key, but I found that if I pushed the pointed lever to the side manually, it opened up just fine despite the spring not doing its job as well as it could.