Complex sentence: Sundown, a maker of primarily suntan lotions founded in 1976 by Carl DeSantis, marketed via mail-order, on store shelves, and other venues, including multi-level marketing.
Split into simpler sentences: Sundown, a maker of suntan lotion was founded in 1976 by Carl DeSantis. The company markets via mail-order, on store shelves, and other techniques of multi-level marketing.