This listing is for two replacement Howse keyed blade bolts, code HL418N which includes two heat treated blade bolts, two hardened lock-washers and 2 hardened jam nuts. We recommend you change your blade bolts when replacing your blades, worn blade bolts are dangerous and should not be used. Make sure you tighten your blades bolts to the manufacturers recommended torque which should be found in your owners manual. If you can not find the torque specification for your mower please feel free to contact us and we will help you locate it.  When properly mounted the threads of the bolt will extend slightly beyond the top of the Jam Nut, if the threads to not exceed past the Jam Nut do not operate the cutter! Remove the bolts and replace with the correct blade bolts!