These are great. I bought them to use to lift my Kreg plunge track saw above the Bora centipede table with 3/4 inch dog holes. The but attaches to the underside t-slot and the dogs are inserted upside-down. They are extremely robust and sturdy, do a good job holding the track up, and allow for sufficient vertical movement to adjust to the height of the track to match the height of the wood you are using. There are multiple 20mm dog hole versions that do something similar, but not for 3/4 inch dog holes. In retrospect I wish I had purchased the centipede with 20mm holes, but these work great with the 3/4.