l hope you can figure this out.
When my son is friend was doing the breaks he noticed that there was a screw that goes into the caliper was missing.
It is a long screw and holds the caliper in place.
With this information and with the best of your knowledge would you happen to know what SIZE screw it might be?
Yes, auto stores will have them but they have several and l dont' wanna make back and forth trips if l get the wrong one.
It is a 90 Toyota Celica

google your sons car and put in brake caliper parts that should let you know if not search the haynes manuals and you should get a good idea.. you can also check the other caliper for the screw and if it is there then pull that one out and take it with you to the auto store so they can match it. that is the best option..

just take one of the old ones to store with you car wil have have more than the one that is missing

u wo not find that sort of thing at a generic parts store. It is too model specific & being it is a brake part u do not want to compromise on something as important as that. It could get u or someone else killed.
Go to ur local dealer & get the correct bolt as it has a special grade hardness,length & thread pitch. Specify if it is an upper or lower bolt as they r different lengths from each other. It is best to never compromise on ur brakes as too much rides on them working properly. The bolt u mention will not cost a huge amount anyway. Good Luck---NS