Yesterday I converted my aero wheels from Shimano to 12-speed SRAM after watching this video DT Swiss Shimano Freehub Body to SRAM XD Driver Swap - YouTube
Was pretty straightforward converting the freehub. However after finishing I realized the Shimano cassette I removed had what appears to be a spacer (silver ring in pic):
Yes that is removed Shimano cassette in a SRAM box.
Was that spacer suppose to be put under the SRAM 12-speed cassette?