I needed a good flowing bolt and had problems with a delrin bolt swelling, I purchased this bolt because it was made of nylatron (far superior to delrin) and it only cost $17.00 half that of other nylatron bolts. To install the bolt with my flush cocking setup, I had to remove the small o-ring at the end of the cocking knob. Everything fit together very well, quite impressive.
At first glance the bolt is o-ring less which some people believe is not good, but IMO it is quite the opposite. The bolt fits quite snuggly in the bolt tube, but there is no binding. Just to see where the bolt failed to recock I ran my reg down to 210 psi and that is where it finally failed, this was about 40-50 psi difference from the Blair's bolts delrin and stock bolts.
Dialed my reg back up to where the gun was shooting 280 fps (290-300 psi) and began to play. I ran 1500+ paintballs through the gun with no breaks and no bolt malfunctions. This has not been the norm with the other 2 bolt.
If you are looking for a good inexpensive upgrade for you gun this would be it. The overall workmanship of the bolt is quite impressive. I would suggest this bolt to all as an option.