My advise after putting the sysem to work on a daily basis is buy the 100" kit, the smart square, 24" rail, and three connectors for each rail section. I just buy the connector extrusion, drill and tap, cut to needed lengths. Its a little cheaper to buy the extrusion and you can make them any lenghth needed up to 5'. With this setup you will have most jobs covered. Don't buy the smart square handle. Buy a kreg clamp or welding clamp or even a tradesman clamp and CLAMP your guide to the workpiece. I don't know why this isn't sold standard this way. This allows one hand on the saw and one hand to hold onto/guide vacume hose and cord. Drill and tap some holes into the smart square and bolt a plywood scrap to it.