Trex 450 feathering shafts sold in pairs with or without dampers in 6 different sizes and will fit all align trex 450s and most clones and similar helicopters.
If unsure on what you need please ask I m happy to help
Picture shows from left to right
4x54mm anti shoot newest version
4x51mm DFC & L
4X51mm pro sport & early flybarless
4x41mm v2,v3,se
3x41mm early pro &v1
4x 54mm no shoulders not shown