Extendable Z20 gearbox barrel sprocket

Extendable Z20 barrel sprocket to be used with fischertechnik. The barrel ends may be used with the regular fischertechnik nr 35113 collet. The barrel can be extented with additional 10mm extentions on a 4mm axle.

I needed the barrel for my gearbox. See https://www.youtube.com/watch?v=JvBxeAs-Xw4