Bob is right. get four plus a couple extras. You will have to drill or ream one side out to fit over the treaded rod. After inststalling them make sure you wire them and PROTECT them during transportation. I went to the field after I had set them up and when I began assembly I noticed that 3 of the six I had put on initially had come off. I found two in the back of the truck but one end of one turnbuckle put the skids on a whole day of flying. Now I use 4 turnbuckle on the bottom flying wires and I leave the safety wires on and I use four adjustable clevisis on the top I attach the top clevis to a special fittting that I made and after I attach the bottom wires I grab the landing wires by that top fitting an sort of stretch it over the pylon and secure it with wire. It's a real easy system and it saves a lot of set up time I just realized as I was trying to expalin this thqt I going to have to figure out how to download pictures and do stuff like that. ugh!!