This is the SRAM X-3 Rear Derailleur for 7/8/9 Speed Mountain Bikes. 

Features: 

• Will work with 7, 8 or 9 speed cassettes, depending on the shifter used

Specifications:

Color: Black 
Weight: 272g 
Cassette Spacing: Shimano/SRAM 7 
Cassette Spacing: Shimano/SRAM 8 
Cassette Spacing: Shimano/SRAM 9 
Shifter/Derailleur Compatibility: SRAM 11 
Largest Cog: 32
Chain Wrap Capacity: 45 
Cage Length: Long