Camber adjustment

[ChrisSnyder4321]

I found this magnetic adjustable level for $10 on ebay. It should allow baselining before disassembly and getting the camber near where it was after replacing the control arms. I don't know what the ad means by "1/2 pack" or why I'd need two.
I appreciate input from anyone who knows more about this or other tools/methods.

Magnetic Gauge Tool for Car Truck SUV Camber Castor Strut Wheel Alignment Brake | eBay

Suitable for accurate checking of the castor and camber angle. after dismantling and re-assembling the suspension or to check the amount of camber change before re-installing. Magnetic gauge attaches to the hub or disc brake.

www.ebay.com

 

[Schurkey]

I found this magnetic adjustable level for $10 on ebay. It should allow baselining before disassembly and getting the camber near where it was after replacing the control arms. I don't know what the ad means by "1/2 pack" or why I'd need two.
I appreciate input from anyone who knows more about this or other tools/methods.

Magnetic Gauge Tool for Car Truck SUV Camber Castor Strut Wheel Alignment Brake | eBay

Suitable for accurate checking of the castor and camber angle. after dismantling and re-assembling the suspension or to check the amount of camber change before re-installing. Magnetic gauge attaches to the hub or disc brake.

www.ebay.com

How does a magnetic camber gauge work, when the description says:

Attention:

Do not include the round magnet.