PM Mainspring No. 17 for Bulova 4AL, 4AB & 5AL - ONYX Steel

PM No. 17 ONYX steel mainspring for Bulova caliber 4AL, 4AB & 5AL and quite likely others, new in envelope. See images for precise mainspring specifications. I specialize in hard to find watch parts so I usually have whatever you might need and all watch parts are unconditionally guaranteed. Images do a pretty good job of representing the item.