Noticed a slow leak underneath my basement sink when the washing machine was draining. What are these pieces called (green arrows), and can I fix this leak myself? The leak is at the location where the metal-looking cylinder (which flexes a bit - probably plastic) enters the white nut-like thing at the P pipe (red arrow). I have fixed basic plumbing before. Or should I just call a plumber?
The top most green arrow is the tailpiece, the bottom arrow is pointing at a slip joint nut with a reducing washer. You can buy replacement kits at most hardware stores for like 5 bucks.