Oregon 90cm SpeedMax Jet Fit Harvester RSN Bar, .404" .080 ga (902SMRS149)

Chain Pitch is the size of the chain, and is defined as the distance between any three consecutive rivets divided by two. Oregon chain is made in several pitches - 1/4" is the smallest, 3/8" is the most popular, 3/4” is the largest. Pitch is important because the drive sprocket must be the same pitch as the chain, and if applicable, the bar nose sprocket. The easiest way to determine the pitch of your chain is to look at the number stamped on the drive link.

Chain Gauge is the Drive Link's thickness where it fits into the bar groove. The gauge of the chain and the gauge of the bar must match. Oregon has several gauges for chainsaws - such as, .043”, .050"", .058” and .063"". Normal wear can make it difficult to accurately measure chain gauge on a worn chain. Always order by the number stamped on the drive link of your old chain to assure correct gauge.

The length of your chain is determined by counting the number of drive links in your chain. Your drive link count has a direct correlation to your bar’s length. Be careful; a bar made by Oregon may take a different drive link count than that of another producer. Here’s a tip: count the number of drive links in the chain you have now, and write that number down someplace where you can find it. Or, if you have an Oregon chain in an Oregon box, the drive link count is stamped on the flap; you can save that flap for future reference.