10-Speed Cassette 11-50T - Silver/Black MTB Mountain Bike Freewheel – Not Your Mom's Garage
Amazon.com : KDKDA 10 Speed Cassette 11-46T/11-50T MTB Cassette 10 Speed Lightweight and Durable for Mountain Bike Mountain Bike Bicycle Cassette flywheel Colour:Gold (Color : Gold, Size : 10s 11~46t) : Sports & Outdoors
Source 9/10/11 Speed Cassette 11-50 T Wide Ratio Freewheel Mountain Bike MTB Bicycle Cassette Flywheel Sprocket Compatible with Sunrace on m.alibaba.com
Garbaruk 11-Speed Cassette for Shimano HG Freehubs – nplus2 cycles