Interesting. The weight insert appears to have been modified, or it's a production change so recent it hasn't shown up on the Halcyon web site yet. The bolts are embedded in the lead in mine and every other one I've seen.
I am not the original owner of my infinity setup. I bought it from wgmotgomery on scubaboard, so I do not know if it was altered in any way. The wing date is 2013. That said, Extreme Exposures sells this 6 lbs Convertible Weighted Single Tank Adapter . This looks a lot like what I have.