I've purchased a few sets of these L track studs https://www.amazon.com/Anina-L-Track-Threaded-Fitting-Mounting/dp/B0D9J3MSXZ?tag=globalgrena0b-20. Does anyone know the type of bolt thats used to secure the studs to the L track fitting? It appears to be a carriage bolt with a flat top. I'd like to have different sized bolts for accessories of varying heights, but cannot seem to find this style anywhere.