Product Name: Best Quality Industrial Threaded Sight Glass Model NO.: jsf Material: Carbon Steel Connection: Female Head Code: Square Shape: Reducing Transport Package.: Wooden Case Material: Stainless Steel Origin: China HS Code: 8481804090 Product Description purpose: jsf series screw type lens suitable for refrigeration equipment, ship, pressure vessel and machinery industry, according to the level of observation device and can be used for pressure for 3mpa,using temperature was minus 40-180 conditions for safe use.