The bolt is an overall length of 55 from the bottom of the head to the end of the threads. The hobbed part of the bolt is 28mm from the center of the hobbed part to the bottom of the head. This M8 Hobbed bolt is used to push the filament into the nozzle and has excellent driving force. This quality hobbed bolt will save you the time and possible frustration of making your own hobbed bolt. 

Package List:

1 x M8 Hobbed bolt

10 x  washer 

1 x  nut