Stihl HT-KM 37″ Shaft Extension On April 19, 2016 0 Comments The HT-KM shaft extension will help you reach tall branches and shrubs that are out of reach. This extender lengthens the shaft by 37″. No more than one extension should be used. $69.95 Product Your Name (required) Phone Number (required) Email Street Address City State Comments *Reservation subject to availability. Someone from Crescent Avenue Gardens will be in touch shortly to confirm this product is available.