Portable Double STD Water Softener Benefits: compact, easy to use, avoids scale build-up, prevents rust stains, reduces water spots, improves rough dry skin, increases lathering of soaps, increases life of appliances and improves taste and odor. Advantages: Quick & easy regeneration, 8,000 grain capacity - standard, 16,000 grain capacity - double standard, handles high flow rates with little pressure drop, inlet flow control, handle included, large mouth opening, cap and plug for storage.