percy seal-4-good gasket question

I just got the gaskets in and there are 4 of them. do all 4 get compressed on one side and i need to buy another set, or do you use 2 on each side and they get compressed or even just 1 on each side and they give you 2 extra. if you have knowledge on the seal-4-good gaskets please help me.
 
I just got the gaskets in and there are 4 of them. do all 4 get compressed on one side and i need to buy another set, or do you use 2 on each side and they get compressed or even just 1 on each side and they give you 2 extra. if you have knowledge on the seal-4-good gaskets please help me.

I installed a set a while back , used 2 per side , worked fine