Dust Collection 4" to 2 1/2" Threaded Quick Adapter By Peachtree Woodworking - PW437 Quickly connects your hose to a 4" O.D. fitting I.e., hoods, gates etc. 4" I.D. x 4" O.D. X 2 1/2" THREADED END Also available is a 4" Quick Disconnect (SOLD SEPARATELY) Also available is a 4" Threaded Quick Adapter (SOLD SEPARATELY)