Vent Systems 3.15 4 5 6" inch Plastic Duct In-Line Reducer - Increaser - Connector - Universal Adapter - Hose Pipe Reducer HVAC PVC ABS Plastic 80-150 mm - Pack of (1) - Amazon.com
Charlotte Pipe 1 1/2 in. x 3/4 in. PVC Sch. 80 Reducer Bushing MPT x FPT PVC 08200 3400 - The Home Depot
NICOLL Réduction extérieure excentrée mf Ø125/80
Fernco 1056-150/125 Reducing 1-1/2-in. x 1-1/4-in. Flexible PVC Pipe Coupling for Cast Iron and Plastic Plumbing Connections in Black - Hydraulic Couplings - Amazon.com