Here I attached our catalog for you check.
As the basic instructions are as follow:
1.   Classes:  Spigot system,  Twist lock system, Single wall , carbon steel 
2.   length:  120mm, 300mm, 500mm, 1000mm, 1200mm. 
3.   ID:   5’’ 6’’ 7’’ 8’’ 10’’ 12’’ ( 125mm, 150mm, 175mm, 200mm, 250mm, 300mm,)
4.   Material: SUS304, SUS316, SUS430, Galvanized steel.

The Rain cap is fitted to the top a standard clay chimney and is used to ensure rain or snow cannot gain access to the chimney while ensuring the exit of the flue gases is not impeded. All Rainbow Chimney rain caps are also fitted with an anti-bird mesh