See the link under the Links & More Info tab to purchase these (the small silver parts) if you don't already have them

Arch support

also awesome

Allows you to shift when installed

SRAM GX Eagle 1x12 Groupset - Non Boost 6mm Offset - Lunar Grey - 10-52T - 175mm DUB Crank netsuite-webdata-created See the link under theThe Eagle GX drivetrain is the easiest way to get into a new 12 speed drivetrain without spending a small fortune compared to X01 and XX1. The Eagle GX kit will help you lose that front derailleur forever and unlock the wide range of a 12 speed drivetrain. This complete kit consists of the new Eagle GX components for integrated system with reliable performance and up to a huge 520% range available with the new 10 52t cassette option. All Eagle