The lower stud in the image is 5/8".
Here's the lowdown on an AirBar:
Upper Mount: 1/2" double shear mount; 1.25" wide
Lower Mount: 5/8" single shear mount; 1.25" wide (1.375" wide without washers)
NOTE: Minimum diameter for single shear mount is 5/8" on loaded applications!
It appears as though the QA1 shocks you have use a 1/2" ID bearing X 1.0" wide.
Our coil overs and Shockwaves use a bearing with a standard 1.0" OD and a 5/8" ID. We then use spacers /adapters to match the mounting hardware and match the almost industry standard 1.25" mounting width.
To do this correctly you need to purchase bearings and spacers from us.
Bearing (if your shocks use a 1" bearing bore):
http://www.ridetech.com/store/index....roducts.search
Spacers:
http://www.ridetech.com/store/index....roducts.search