Martingale out of faux leather. Around the neck is openable and adjustable with buckle.
You can choose a built-in or detachable martingale part (where you can detach the parts with clasps).
Measurements about: around the neck 55-70 cm (adjustable), down strap 17 cm, martingale parts 10 cm. The martingale parts have keyrings, so they're easy to slide to reins that are not detachable from the bit.