DO Not use 2" boards - The bolts for the large holds will not fit in 2" boards. Very disappointed, as we built a wall with 2"x6" planks only to find out that the holds will not attach through that thickness. NO where in the product description, specifications, instructions did it specify the recommended board thickness for attaching these holds. I assumed that with a 2" bolt they would fit but the large holds are too thick and will not connect through the boards. The small holds do connect. The manufacturing of the holes should be the same for the large and small holds. Off to the hardware store to spend additional money. :(