Silicone 90 Degree Reducing Elbow 4" to 3" ID Gloss Black - One Short Leg
Five-ply reinforced silicone for high strength - much stronger than 4-ply elbows. 7/32 wall thickness.
This is the special short radius version with one short leg, for locations where you have minimum space to install.
Recommended clamps are 94100-0350 on the small end and 94100-0450 on the big end.