This is a new ligature from k plume. It's for alto saxophone rubber mouthpieces (also usable on slim tenor mouthpieces). It's probably not yet listed in their lineup. It seems to be a model created with the intention of keeping costs down while still using plenty of expensive sterling silver and platinum. Its features include a significant increase in resonance and volume. While the blowing feel is smooth, a gorgeous, rich depth is added to the sound. It gives the impression of being rich in lower overtones.