These light weight wrenches are CNC machined to have exact fit over 4mm turnbuckle adjustment nuts (like ones found on Traxxas Slash, Rustler, Bandit and Stampede, or all popular on-road touring cars today) and the 5mm turnbukle adjustment nut on the T-Maxx, E-Maxx and Revo, also any 1/8th buggy using the 5mm size turnbuckle. Great tool to have for tuning your favorite R/C racing machine.