This good quality U20 header gasket.  Superior to those sold by budget vendors.  These are .125" thick and often can be re-used.
 
Great price!
 
Since we work on so many roadsters, we know that changing the header gasket is a pain and suggest using the best gasket you can buy!
 
We suggest these instead:
 
 
Premium Header Gasket U-20 | datsunrestoration (datsunrestorationproducts.com)