PLEASE NOTE: SOME OF THESE ARE NOW IN GREY
These are specially made for Lambretta upgrades in the U.K. from top quality gasket material, with far superior sealing qualities. Specifically used for fuel and oil under pressure unlike standard gaskets. 
The other outstanding quality of these crankcase gaskets is they do not rip as easy as the chepaer versions and therefore can be used over and over again, just spread a thin layer of engine oil on both sides to help it seal.
Available in  0.75mm thick - this is thicker than 0.5mm standard gasket, so can help if you are having problems with the kickstart shaft rubbing on the clutch top plate - 1mm thick are available on request, these are more expensive. 
The gasket material is made from aramid and man-made mineral fibres bonded with nitrile rubber. Suitable for sealing out oils and fuels, also water, steam, gases and many chemicals!
 
Complies with test requirements of BS7531 Grade Y
Price includes VAT @ 20%