This is an adapter for a RIDGID shop vacuum with 2" hoses. This is to connect the small ends of two hoses so that the vacuum can reach a wider area.
One end of the adapter has a sawtooth section that's grabbed by a tab on one hose. The other hose didn't have that so the other end is smooth.
Printed in durable, earth-friendly PLA in your color of choice.
Design credit to CFLBob@Thingiverse: https://www.thingiverse.com/thing:4857279