PLEASE NOTE: This cone reducer is specifically designed to work exclusively with 4 inch and 2-1/2 inch hoses, It is NOT intended to fit or accommodate a 2-1/2 inch OD or 4 inch OD dust collection equipment port directly (which would require 70149 or 70148 Flex Cuffs) FUNCTION: A handy double sided adapter that allows you to from your larger (4 inch) dust collection hose to a smaller (2-1/2) shop vacuum hose branch line. The 2-1/2 inch. opening also allows you to fit for , and a variety of other wet/dry vacuum cleaners PREMIUM: Made with high quality ABS plastic for long-term durability and to withstand the abrasive nature of workshop dust collection 4 inch to 2-1/2 inch Dust Collection Hose Reducer