Irritrol's TW-LA-1 Lightning Arrestor comes from the Rain Master Twice Series. This arrestor is for use with Rain Master Twice Series Controllers, and should be installed once every 600'. 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.