FITS MINI BULB HORNS...Just screw it on and start honkin'! HARD-TO-FIND PRODUCT: This small "mini" replacement bulb delivers an extraordinarily loud honk for its size. IMPORTANT: Reed screws into horn, not the bulb. So if your reed screws into bulb, then our bulb will not work (see photos). FITS THESE HORNS: This bulb fits "mini" vintage car, taxi, antique, old-brass and clown horns. Also fits Dobani bulb horn product code: BULBM. LARGE OR MINI: We offer bulbs in just two sizes: Large and Mini. Large is the "standard size" bulb and fits most bulb horns. The Mini is for little "bicycle-size" horns. NOTE: A Mini Bulb does not generate enough blast for standard size horns. So even if our Mini Bulb fits your standard size horn, you should find a bulb designed for your specific horn instead (prices typically start at $20.00), or retrofit Large Bulb. HOW TO CHOOSE BULB SIZE: 1. Measure Bulb Tube. If outside diameter is 11/16" (17.5 mm), then get Large bulb. If outside diameter is 5/8" (15.9 mm), then get Mini bulb (see note above). 2. Measure Brass Fitting. If horn fitting OD is 5/8" (15.9 mm), then get Large bulb (same as Large bulb tube ID). If horn fitting OD is ~9/16" (14.3 mm), then get Mini bulb (same as Mini bulb tube ID). 3. Measure Bulb. If bulb circumference is 11-1/2" (29.2 cm), or length from base to neck is 5-1/4" (13.3 cm), then get Large bulb. If bulb circumference is 8-3/16" (20.8 cm), or length from base to neck is 3-1/4" (8.2 cm), then get Mini bulb. WHY CHOOSE THIS BULB: If you want a brand new pre-tested budget-priced, antique-style, spare replacement bulb that fits your Mini Bulb Horn plus other smaller bicycle-size bulb horns, then this bulb is for you. TECHNICAL SPECS: Bulb Diameter: 2-3/4" (7 cm), Bulb Circumference: 8-3/16" (20.8 cm), Bulb Length to end of brass collar: 3-1/4" (8.2 cm), Brass Tube Length: 1-1/4" (3.2 cm) more or less, Brass Tube ID (screw fitting): 9/16" (14.3 mm) at 28 tpi (threads per inch), Brass Tube OD: 5/8" (15.9 mm).