This is the duty model, not the competition model.
Will fit in standard carbine buffer tube. Made for use with standard weight bolt carrier group.
I've used it for a total of about 200 rounds total in my 13.9" and 12.5" mid length rifles. I was having feeding and ejection issues with my IWI Zion 12.5" mid length while suppressed and unsuppressed. This dead blow buffer solved those issues and it ran flawlessly. It comes in the original packaging with the two spacers (not really needed). I highly recommend removing your buffer retainer pin. You don't need it with this buffer and it makes it a pain to remove the buffer.