Hi Conner, Basically all I did was fill the 1 1/4 inch opening of the male fitting with the smallest reducer I could find. What I wanted to do was bolt the fitting to the cross member. I used a fender washer because the thru hole in the reducer was too large for the nut and bolt. It worked great as I was able to sock the fitting securely to the cross brace. I hope this answers your question. If you are making an NTrak module, - One word of caution is to carefully total up all the dimensions of your components so you wind up with the 40" plus/minus required track height. The rule; measure twice, cut once - in this case it's measure thrice, glue once.