Originally posted by zoolander The second one was a K-7, but I believe they shared the same af system.
The K-7 had SAFOX VIII+, the K-5 had SAFOX X, the K-5II had SAFOX XI+. That's 8+, 10, and 11+ in case Roman numerals are confusing.
I got a third party grip for $54 when I got my K-7, just to see if I liked it, and in case I ever had to worry about batteries. It spent a lot of time in a drawer and the controls don't work any more, but the battery part still supplies power. I think now I would buy the genuine one if I was buying one for the controls. For my shooting, I don't really need the extra battery often. If I was going to a remote location, I'd again get the Pentax version, because it retains weather sealing and is more reliable.
Someday I might make a battery holder for two spare batteries, just a tripod screw and storage for the batteries and some cards. It wouldn't have connectors but swapping batteries is easy.