As much as bolt fixings and fasteners are important, preventing them from becoming loose is also important. The loose behaviour of bolts could be many but mostly it is because of improper tightening or wear and tear due to friction and vibration. If the bolts are not tight anymore but they need to stay tight in their respective places then two nuts can be used. For this reason the two nuts used should be chosen in such a way that one nut is of a regular size while the other is smaller in size. The regular sized nut is used first. Then the smaller nut or the jam nut is used so that the nut remains in its place for a longer time. It reduces friction and keeps the nut locked in its place. While placing two nuts in a bolt, the smaller nut is first placed followed by the larger one.