This is a new TsuMura LIGHT-WEIGHT 20" 3/8" pitch, .050 gauge, 72 drive link Professional Guide Bar. This LIGHT WEIGHT guide bar is 20% lighter then a standard bar of this size. The guide bar is built with staggered, dove-tailed notches that are packed with hard resin which reduces the weight by 20%. This guide bar works on the large Echo models like the S451, CS452, CS500, CS501, CS501EVL, CS510, CS510EVL, CS550, CS5500, CS550EVL, CS610EVL, CS590 Timberwolf, CS60, CS60S, CS600, CS600P, CS601, CS602, CS610, CS610T, CS620, CS650, CS660, CS670, CS6700, CS680, ,CS701, CS702, CS706, CS750, CS8000, CS800P and QV8000. This guide bar also works on Poulan models 203, 245, 3400, 360, 361, 3700, 375, 3800, 3900, 395, 400, 4000, 4200, 4400, 450, 4900, 5200, 5400, 5500, 670 Note: Your chainsaw must be equipped with a 3/8" pitch sprocket for this bar to work properly! Replaces Oregon guide bar number 200RNDD176 TsuMura guide bars have the reputation of being the highest quality guide bars made today! They were sold for 40 years under the TOTAL SUPER bar name. Made from the finest quality, high-carbon tool steel. Sprocket Tips feature large-diameter sprockets encased by heat-treated carbon steel. Solid one-piece milled high-carbon steel bar that has a brushed steel finish. Rails are precision-ground to uniform tolerance. Longer tip reduces chain "hammering" of bar rails for longer bar life. The TsuMura Pro "FV" tip has been engineered to provide long service life, with a thick sprocket and strong cogs that stand up to hard use and extreme temperatures. The sprocket tip is firmly held by three rivets and is recessed into the bar body for excellent stability and accurate chain feeding.