BIO SLEEP CONCEPTNatural Latex Foam Mattress Foundation (Cal King, 5 inch)

I bought a new Latex Mattress, and my existing box spring was not going to work with the new mattress. I called the mattress folks and they confirmed the spacing on this box spring was fine for their mattress. I ordered the shorter box spring (5.5") because my existing set up was too high, but I didn't account for the lower height of my new Latex Mattress and everything ended up being too short. So that was an issue. But the main problem was in the California King size, I definitely felt a "bow" in the middle after my new mattress was installed over this box spring. I was rolling down towards the middle of the bed. Not good. I had support down the middle from underneath, but it wasn't enough.I will say the box spring was very easy to set up - I am a woman and I did it myself - and it was nice and light to move into the bedroom and get into place. I didn't send it back - how the heck would I have done that? - way too complicated so I sold it on Craigslist to someone else.