Porcelain pin insulators are used on medium voltage and high voltage distribution lines, and this type porcelain pin type  insulator is with the voltage ranges from 6kv to 36kv.

Porcelain pin insulators introduction:
Zinc Sleeve to prevent pin corrosion
High Leakage and Fog Bowl Pin Types
Two types of standard insulator pins, steel or lead head are available.
ANSI C29.5; ANSI C29.6, IEC60383 and BS137
ANSI 55-1, ANSI 55-2, ANSI 55-3, ANSI 55-4, ANSI 55-5, ANSI 55-6, ANSI 56-1, ANSI 56-2, ANSI 56-3, ANSI 56-4, ANSI 56-5

Porcelain pin insulators are widely used for distribution line and other electric line. With a spindle or pin, the insulator can be smoothly mounted on a supporting structure. These pin type insulators are all single or multi piece designs with porcelain threads, a design which years of field experience has proven to be the best.