These derailleurs have been mounted on new bicycles but removed before the bicycle was used. There may be tiny marks from installation but nothing that can be seen from more than a few feet away. 

NOTE: These DO NOT included the B Screw Adjustment Tool. To install this rear derailleur, you can set the B screw to the same distance as your last derailleur or put the derailleur in the second largest cog and set the tip of the derailleur pully teeth 3mm away from the tip of the largest teeth on the largest cog - See last photo or the SRAM owner's manual on line for part RD-GX-1-B2.

We have the matching cassette here: SRAM GX 10-52t Cassette XG 1275 12 Speed Eagle 520% XD | eBay

Specs:

For 10-52t / 520% SRAM Eagle Cassettes

Type 3 roller bearing clutch

X-Actuation cable pull ratio - For SRAM 12 speed mechanical mountain bike drivetrains

Lunar color

Backwards compatible with SRAM 10-50 12 speed cassettes

294 grams - actual weight on the official BuyCycleStuffOnline postage scale