Shimano Tourney TY300 6/7 Speed Rear Derailleur – Rivet Mount TX models come with Smart Cage which gives MegaRange compatibility with a shorter derailleur cage. Model: Shimano Tourney RD-TY300/TZ50 Rear Style: Road Drivetrain Speeds: 6 Cage Length: Long Chain Wrap Capacity (teeth): 43 Color: Black Rear Der/Shifter Compatibility: Shimano Mountain Rear Derailleur Mount Type: Dropout Claw Hanger Largest Cog: 34 keyword search: Replaces rd8162 Drivetrain Speeds: 7