GRX RD-RX400 Rear Derailleur - 10-Speed, Long Cage, Black, With Clutch Seat pack And as you were probably

And as you were probably wondering

2pc cover with aramid sides

Factory tuned compression (in open position) provides the highest level of XC performance

Using a PF30 or BB30 bottom bracket with outboard bearings is REQUIRED

LockTight Wings

GRX RD-RX400 Rear Derailleur - 10-Speed, Long Cage, Black, With Clutch Seat pack And as you were probablyGRX RD RX400 Rear Derailleur A Shadow RD+ chain stabilizer prevents chain slapping and drops The gravel tuned clutch tension helps to provide smooth and reliable mixed surface shifting Stabilizer can be turned on off to match terrain Compatible only with 10 speed ST RX400, ST 4700, ST4720, ST 4725, ST RS405 and SL 4700 shift levers