Irritrol's 533 Adjustable Flood Bubbler comes from the 533 Series. It has a 1/2" FNPT thread. The 533 has a flow rate of 1.36 - 5.9 GPM. It has a pressure rating of 20 - 40 PSI. Irritrol has made their name as a brand by selling and marketing exclusively to the professional installer, as a result their products are geared to be dependable and durable. Irrirtrol is now making their products available to you through our website. If you are looking for a product line that will last year in and year out, Irritrol is the brand for you.