The Genuine Fanatec table clamp is awful. Three M6 screws the thickness of your desk plus 10-15mm (so for a 30mm thick desk you would need a 40-45mm screw).
CREW_UK Fanatec CSL DD or GT DD Pro Wheel Desk Playseat Table Bolt on Clamp
Fanatec CSL DD. GT DD Pro Shaft Clamp. Runout disconnection fix. QR1 or QR2
4 M6 T-nuts + Hex bolts for Fanatec Csl DD / GT DD base or 4040 Profile
Fanatec CSL DD QR2 5nm, CSL Pedals, CSL Table Clamp + Unofficial 8nm boost kit
8Nm Boost Kit 180W Power Supply For Fanatec CSL DD GT DD Pro UK Plug
QR2 Base Side Type C for Fanatec CSL DD & GT DD Pro Wheelbase *BRAND NEW*
