18" .325" .063" Gauge 74 Drive Link Stihl Rapid Duro 3 Carbide Chain Applications: The RD3 chain is especially suited for cutting dirty wood, treated wood, roots and hardwoods. The first STIHL carbide-tipped .325" saw chain stays sharp up to four times longer than standard chains. In addition, the STIHL RAPID Duro 3 is a low-vibration chain with a reduced kickback tendency. To use this chain your Bar must be 18" and use a , 74 Drive Link, .325"Pitch, .063" Guage Chain