XRAY - Model racing cars

Hello
On this shock absorber , on bottom side , we have the choice between two sealing
2 O-ring and 2 thin shim or 1 O-ring 1 thin shin and 1 thick shim.
which is the difference between these 2 assembly. Which is the best
thank you
Jacky

1 O-ring has less friction so it will react faster and better on a smooth but still a little bit bumby surface. The chance of a leak is bigger with one O-ring....

Thank you Roelof but i haven't the choise , there is only 4 O-ring in my kit

That's correct if you want two seals you need to buy more o rings

1 o-ring set-up is more smooth and this is always the best option.