This is the Sonor MH-BDPA Bass Drum Percussion Adapter. If you are looking for more flexibility with your setup, this add-on offers ultimate maneuverability, unbeatable roadworthiness and an elegant, refined style. The MH-BDPA allows you to mount your Cowbell to bass drum hoop with adjustable angles and lengths. It features Sonor's Docking Station Design, along with RPS Rubber Protection Inserts for better drum hardware protection. This is German engineering at it's finest.