1. There are many port sizes: 1/8" 1/4" 3/8" 1/2" 3/4" 1".

2. It allows the fluid to flow in one direction ONLY.

3. It is prevent backflow due to sudden in pressure or decrease in air consumption .

4. There is large valid area of section.

5. The spool is made of POM valve''s core sealed with rubber and it has a compact structure.