The Clouser is a popular saltwater fly for fishing for striped bass. The Clouser is a weighted fly; choose it when the fish are deep.
The Clouser Deep Minnow Fly was originally designed by Bob Clouser to catch smallmouth bass in the Susquehanna River. Bob wanted a fly that dove down during the pause in the retrieve. His innovative trick to make this happen was to add metallic dumbbell eyes to the fly. This resulted in a streamer fly with weighted prominent eyes that performed as he desired. The fly has an action all its own, similar to that of a jig. Also, the hook rides up making it somewhat snag proof. Bob's favorite color for the Clouser fly, especially for striped bass, is chartruese and yellow, with gold crystal flash.
Bob Clouser developed a particular stripping method for fishing with this fly called the Susquehanna Strip. This technique, as described in his book, accelerates and pauses the fly during the retrieve so that when stripped back, it darts like a fleeing baitfish. With this technique, strikes increase tenfold over a steady stripping retrieve. Cast, and when the fly hits the water, drop the rod tip down to 6 inches from the water and make a long strip of 3 to 4 feet. As you start the strip, bring your arm back along your side. When your hand reaches your leg, quickly turn your thumb rearward to accelerate the strip. Ending the strip with a speed-up-and-stop portrays the erratic escaping movements of a scared baitfish. The quick acceleration frees the fly from the leader. The fly stops and turns down because of the weight of the metallic eyes. The strike comes on the drop.
More information about Clouser Flies can be found in Bob Clouser's book Clouser Flies: Tying and Fishing - The Fly Patterns of Bob Clouser.
If you are going to fly fish for striped bass, make sure you have some Clouser Deep Minnow Flies.