Schubeck Racing Engines & Components makes three types of Hi Performance flat valve lifters. 

The first and most common are those, often referred to as "tappets" and are used on flat lifter cams in early model Chevy, Ford and Chrysler engines.  The second type are mushroom lifters, used in air cooled engines, such as Volkswagen.  Last, the third type is a lifter for late model overhead cam engines called cam buckets.

We   also make flat valve lifters for imported engines such as MG, MGB, Spitfire, etc.