The most commonly used string in racquetball. Bundles of micro synthetic fibers are twisted together, similar to natural gut. Nylon multifilaments are typically more comfortable than solid core strings due to the cushioning effect of hundreds or even thousands of micro fibers. Resultant effect is a soft and comfortable string, recommended for players suffering from arm problems who don't want to pay the high price for natural gut. Normal use causes multifilament strings to fray, like gut, which can be alarming to players switching from solid core strings.