Help ID sink drain to copper drain pipe adapter

[MacGyver]

My house is plumbed with copper drain piping. The 1 1/4" sink drain goes into some kind of adapter which appears to seal against the 1 1/4" pipe with some kind of rubber seal.

Can anyone explain what this adapter is called and how I would go about changing the pipe that goes into it?

Thanks for any help.

 

[Reach4]

It looks like either a slip joint nut, or something else serving as a slip joint nut. I understand it does not look like a normal slip joint nut. There would also be a slip joint washer.

I am thinking either of these could replace this if the OD on your thread is 1.66 inch.

Oatey 1-1/4 in. Sink Drain Pipe Plastic Slip-Joint Nut with Rubber Reducing Washers HDC2798C - The Home Depot

1-1/4 in. Slip Joint Nut and Washer are designed for use with plastic tubular slip joint connections. Durably constructed, they are built to last. Oatey products have earned the trust of plumbing professionals

www.homedepot.com

Oatey 1-1/4 in. Sink Drain Pipe Zinc Slip-Joint Nut with Rubber Reducing Washer HDC8030C - The Home Depot

Make tubular drain applications a breeze with the 1-1/4 in. Slip Joint Zinc Nut with Washer. The nut features die-cast zinc construction with chrome plating for a long life. The included washer is durability

www.homedepot.com

The thing that connects between there and your lavatory tailpiece would be a 1-1/4 slip joint trap. Available in plastic or chrome-plated brass.

If the OD on your thread is 1.9 inch, then similar widely-available choices exist.

You would unscrew the existing nut by turning the hex CCW.