Those are aftermarket allen head bolts. I usually get rid of the stock bolts and go with grade 8 when I can. Had those spares laying around and used them since I had extended the back rest about 4 to 5 inches higher for the GF. She found lots more comfort with the back rest higher. Then when I went with the KIng Tour Pak, the back rest had to come off. Now she really likes the Pak with the arm rests and feels "safer" with the Pak back there.