Straight Bulb Horn w/Extra Bulb Deluxe Package includes DOBANI Straight Bulb Horn and DOBANI Rubber Bulb. DOBANI Straight Bulb Horn, 2 1/2" bell, 17" length. Brass bulb horn with removable reed and bulb. Uses a bulb with a 5/8 inch fitting. You should expect your brass instruments to have, or develop, an attractive antique patina. DOBANI Rubber Bulb, This is a replacement rubber bulb for a taxi horn with a 5/8 inch fitting. It is approximately 4" in diameter with a brass tube of approximately 5/8" in diameter and 1 3/4" in length.