I'm going to replace this part on my car, as it seems to be leaking somewhere, either the tube or the connection, but difficult to see. But since they will be fixing other things on the car, and I found an aftermarket version at a reasonable price, I will proceed.

 

Nissan uses these washers, which are 640 baht for the pair, and not easily resourced in aftermarket, while 4 copper washers from the same dimensions would set me back 50 baht in total.

Is there a particular reason why Nissan makes them in this shape, and I shouldn't use separate washers?

Cojoined not needed, just use seperate.... same end result.