The Imperial Industries Self-Contained Slide-In unit offers an original freshwater tube, with a design that allows for equalized weight distribution of water and waste. Stock sizes include 300-, 450-, 550- and 650-gallon capacities, each available in steel, stainless steel or aluminum models. It can be used for portable restroom maintenance, grease service and oil spill cleanup. 800-558-2945; www.imperialind.com.