When replacing the cam belt the standard M14 bolts can become damaged or seized .
I use these replacements as they have a larger hex head for a better purchase and it's adviseable to replace as they require a high torque setting when re-fitted. Always clean the threads out in the mounting with a M14 tap to ensure the correct torque is achieved.
If can't screw them in by hand they won't torque up correctly and they can fail and drop your engine. 
Do not use an impact gun to tighten these!
Sold as a pair i.e 2