As I stated in another current thread, I was given a lot of unassembled/unused wood frames. The bottom bars are what I think is called a slotted bottom bar. I don't plan on using these because I will be using plasticell foundation, and i am guessing the foundation would just fall right through the bottom bar. The top bars are the wedge style. What do/did beekeepers use this kind of bottom bar for? Thanks, juzzerbee.