Porcelain pin type insulators are one main of pin insulator having many types in ANSI standard, such a 55 and 56 series. ANSI pin type insulators are made from porcelain or polymer.

55 and 56 series ANSI Porcelain pin type insulators have 

◆ ANSI 55 series: 55-1, 55-2, 55-3, 55-4, 55-5, 55-6 

◆ ANSI 56 series: 56-1, 56-2, 56-3, 56-4, 56-5, 56-6

In the other standards, such as South Africa, the porcelain pin type insulators have P-11-Y, P-15-Y, P-22-Y, P-33-Y, PW-15-Y, P-22-Y, P-33-Y 

In ANSI specification the Porcelain pin type insulators shall refer to a unit or a stack of one or more units.