The 1st Model, 1939-1940, originally called the #10 Table Lighter De Luxe, is 4.5 inches tall and has a long fluid insert extending to the bottom of the "one step" base. It is rare.

The 2nd Model, 1947-1949, is 4.25 inches tall, has a tall insert like the 1st Model  but two steps. 
This one has an Town & Country engraved mallard.

The 3rd Model, 1949-1953 is 3.25 inches tall with a tall insert. This one depicts Ernst, an organ grinder's monkey.

The 4th Model, 1953-1979 is also 3.25 inches
tall but uses the same insert as the regular
 size pocket-model Zippo.  This two-sided
Barcroft features Charlie Chaplin, the
"Little Tramp".