Oregon 560507 PowerSharp Replacement Saw Chain Kit for CS250 with Onboard PowerSharp System, 14" The Oregon Power Now Replacement Saw Chain includes a sharpening stone that is designed to be used ONLY with the Oregon Power Now chainsaw Top-sharpening design allows the cutters to be sharpened in seconds on the saw, Pull the Power Sharp lever on the Power Now chainsaw for 3-5 seconds Chisel-style cutters deliver efficient cutting and excellent stay-sharp Ramped depth gauges and ramped guidance drive links deliver smooth cutting action and low-kickback performance The Oregon Power Now 560507 Replacement Saw Chain, Power Sharp 14-in (includes sharpening stone) is low-kickback per ANSI B175.1 & CSA Z62.3