This Real Clean™ 18" Concave Microfiber Mop Head with Universal Collar Lock System is designed for heavy use. The concave design helps push the water under the mop frame into the Microfiber mop pad for maximum cleaning power. It makes it easy to push this Real Clean™ 18" Concave Microfiber Aluminum Mop around all areas of your cleaning surface. Built to last! Call us directly for bulk discounts at 1-866-888-8185.