This square FIA-Approved Backing Plate from Sabelt has 7/16-20 female threads to accept a standard forged safety harness mounting eyebolt.
Alpinestars Flow Helmet Bag with Ventilating Blower - Pegasus Auto Racing Supplies
CCMI0016 Sabelt Eye-bolt back plate : Automotive
Grayston harness eyebolt back plates are made from high quality heat treated carbon steel., Essential for seat belt fitting, 65mm x 65mm x 3mm
Grayston Harness Eyebolt Back Plate
楽天市場】サベルト アイボルトバックプレート シートベルト取付け用 FIA車両規則準拠 7/16 20 UNF Sabelt : Star5 スターファイブ
FIA Harnesses - RallyShop Italy
SEAT FASTENING KIT
Seat Belt Hardware Kit #1 (pair of 7/16 bolts and nuts) - OEM Seatbelts
7/16 UNF Harness Eye Bolt - Racetech Seats USA
Sabelt Seat Mount Steel
407005 EYE BOLT- SINGLE
Raceparts UK Ltd 2018 digital catalogue by racepartsuk - Issuu
CCMI0023 EYE BOLT – SINGLE