There is provided a fast acting subminiature cylindrical fuse having a cylindrical cover substantially locked onto a cylindrical base. The locking mechanism for the cover comprises a plurality of grooves and a plurality of corresponding projections on the internal surface of the cover and the external surface of the fuse base. The lock projections have a relatively straight diverging upper surface and a rounded bottom locking surface. The fuse base has a spacing ridge on the bottom thereof that spaces the fuse bottom surface above a circuit board surface. The fuse also has a plurality of pressure relieving passageways extending from inside the fuse to the outside of the fuse.