This is a specially made base gasket in with the correct stud spacings for the 200/225 block Lambretta engine casing. 
These have been checked to make sure they are correct. Big surface area around ports for porting. Essential you get the correct base and head gaskets for setting correct port timings and squish height.
 
These are available in 2.5mm and 3mm, please choose from the dropdown menu below.
0.5mm, 1.0mm, 1.5mm and 2mm are also available on this website.