Save your money and get the original grip even though it's more expensive. The third party battery grip will make your expensive K-5 look and feel like a cheapo camera when it's attached.
The buttons are crappy, the plastic will eventually become shiny, the paint will wear off, the on-off dial is loose, the battery door lever will snap off, and it's not weatherproof.
Thankfully I managed to DIY fix my battery door with the spare AA battery tray, but now that I bought the original D-BG4, this grip has been packed up and kept away, maybe as a backup someday.