First Two Numbers — Designates air terminal diameter
Second Two Numbers — Designates air terminal length
Prefix A — Designates Aluminum
Prefix C — Designates Copper
Suffix ST — Designates Safety Tipped
Suffix X_ _TH — Designates Thread Length

Field bends are permissible but must not exceed 90 degrees or have a radius of bend less than 8 inches.

Example:

A1224X12TH

Aluminum 1/2″ X 24″ air terminal with 12″ air terminal, 12″ of threads, and hardware

C1232STX14TH

Copper 1/2″ X 32″ air terminal with 18″ air terminal, safety tipped, 14″ of threads, and hardware

C5836X18TH

Copper 5/8″ X 36″ with 18″ air terminal, 18″ of threads, and hardware

Air terminals are made of solid Aluminum or Copper in one length furnished with compatible nuts and washers.