An essential spare for all D3 owners! Many people have experienced issues with wear of their front belts. If you have broken your belt or stripped the teeth then your going to need to replace it with this belt. Pretty easy job if you've built your own D3, if you purchased yours already built it might be a bit more difficult as you need to strip the front bulkhead down to access the front spool! But just check your instruction book for how it goes together then reverse the process! I always keep one of every belt as a spare, just in case.