The ideal choice for any musical genre, the Jo-Ral Bass Trombone Straight Mute produces a smooth, distinct tone It is free-blowing in all registers and designed to fit all tenor trombone bells. The Jo-Ral TRB-4A Bass Trombone Straight Mute made of spun aluminum, and has been tested to perform evenly in all registers. Jo-Ral mutes also feature neoprene-enhanced composite cork pads that provide extra durability. The result is a more pliable cork that grips well and doesn’t dry out, become brittle or break off—so it lasts longer while easily accommodating fine adjustments for a perfect fit.