We bought the King-sized bed.  The frame is made of an edgebanded plywood - it isnt particle board and it isnt solid wood plank.  It looks very nice.  

The slats are a light pine type wood.  So is the support beam that runs down the middle.

Assembly was very easy.  There are only 4 outside pieces, the slats and a support rail.  

It is a low profile bed.  It sits about 11 off the ground.  We bought the Gold Bond 8 mattress and it fits into it perfectly on the sides, and about 12 inch gap top and bottom.  

The bed is sturdy and doesnt creak.