Amazon.com: Thule T-Track Adapter 697-4 for attaching The roof Box Directly in The T-Slot 697400 : Automotive
SP-SBH-Kit Dual-T Head Conversion Adapter with Wing Nut for Garmin 17mm Ball | eBay
8020, 3376, 10 Series, 1/4-20 Steel Roll in T Nut with Flex Handle - T Slot T-Nut Accessories for T Slot Aluminum Extrusion - Hardware Nuts (10 Pack): Amazon.com: Industrial & Scientific
Ultralight 1/4"-20 x 1.25" T-Bolt for BA-TG Ball Adapter