SRAM ROAD: eTap AXS™ BlipBox™ System Installation - YouTube
eTap AXS Wireless Blips | EC-BLIP-B1 | SRAM
Bent Up Cycles - SRAM etap blip box. Technically, you only need this and don't need the blips. But I have found that shifting with the blips by the brake levers works
Sram BlipBox eTap AXS D1 Control Box | Alltricks.com