These worked quite well to do what we needed them for.  It caused some frustration, since it instructs you to use the screws from the crib to attach these, but since the way our crib was configured, the screws went through much thicker wood, the screws we had were much too long.  They weren't able to be sawed off because then all the threading part would have been gone, making them useless.  We ended up figuring out a way to attach it and now the cribs looks great converted to double beds.  I understand why they tell you to use the included screws - so that they are the right fit for the included holes in the crib, so I'm not sure how you get around this... but it was sort of frustrating. We also ended up using memory foam mattresses with no box spring (so the beds are low to the ground and accessible for our small kids), we just bought more wood to make a bunch of additional slats/supports across, and it works just fine.