I received this extra with a Cannondale frame I bought.

SRAM made the Ai spindle specifically for Cannondale Ai gravel frames that used PF30A-83 BBs ('20-'24 Topstone, SuperSix, maybe others).  PF30A (73) Ai road frames accept regular Sram Dub Road spindles and can't use the Dub Road Ai spindle. The crank spindle is not integrated and can be exchanged for another SRAM spindle so that the crank arms can be used on any bike.

AFAIK the 4-bolt interface is for 1x, so here's your budget 1x gravel setup.

YOU NEED TO BUY SPACERS.  9mm for NDS and 6mm for DS for PF30A-83 gravel frames according to "Dub Cranksets and Bottom Brackets" technical document on the SRAM site.  They are a few dollars on ebay.

Some hard earned notes for the confused:

Cannondale Ai is a frame standard used by Cannondale in the early 2020s wherein the whole rear axle is shifted axially 6mm to the DS for spoke tension balance of the rear wheel.  PF30A is a PF30 bottom bracket which is +5mm wider on the NDS, so as to make the bottom bracket stiffer.  PF30A can be 73mm wide, 79mm, or 83mm.  When it is 83mm wide, it is called PF30A-83.  Ai is wholly unrelated to PF30A.  PF30A (73mm or 79mm) frames can be Ai or not Ai.  It happens that all PF30A-83 frames are also Ai.

Ai shifts the rear cassette and therefore the whole chain line +6mm to the DS (chainline being measured from the center of the seat tube).  That PF30A-83 is wider than either PF30A has no bearing on the chainline. Both technologies (axle offset and wider bb) require the crank spindle to be extended.  To address this, SRAM made the Dub "Road Ai" super long spindle just for frames that incorporate both PF30A-83 and Ai.  It is wider than both Dub Road and Dub Road - Wide.  If you have a PF30A frame with Ai, you can use a Dub Road or Road - Wide spindle with different spacers, but you can't use Road - Ai (insanity). 

Shimano Hollowtech cranksets have an integrated ~110mm spindle, which is too short for any Ai frame.  There are rumors that the Cannondale racing team used Shimano XTR mtb cranksets with long spindles paired with regular Shimano road RDs to solve this problem.

Cannondale quietly stopped making Ai frames in 2025 so that people didn't have to crawl web forums for hours to figure out why their wheels and cranksets didn't work.  This is a legacy crankset.