RGC Straight Mute for Trombone in Cherrywood. Driven by their passion for music, all the RGC mutes products have emerged after a long process of study and research on materials and the most appropriate shapes. The final result has been the choice of cherrywood and ashwood as raw material, which provide a sound that cant be matched or imitated by other materials. All the RGC mutes are handmade in Valencia, Spain.