This pack of 12 Boston Bridge Saddle Height Screws are used on bent sheet steel saddles and modern block style saddles on Stratocaster style tremolos, fixed/hardtail guitar bridges and modern (non ashtray) Telecaster bridges. These are handy spares for lost or damaged parts and the choice of shorter length screws allows the string saddles to be set low without having the screw high above the saddle surface, making them more comfortable on the hand while playing. They have a metric 3 mm thread which makes them suitable for use on almost all guitars made in Asia e.g. Squier, Schecter, ESP/Ltd, Ibanez, Jackson etc. (please note they will not fit made in USA bridges like Hipshot and will not fit the larger style screws used on some bass bridges). The saddle height screws adjust with a 1.5 mm Allen key/hex wrench.