This is a Y pipe connector, size M20/27.
The pitch is 14G (aka 1/14in = 0,071in = 1,81mm)
The tube thickness is 3mm

As water may leak from between the layers, I dipped it into hot paraffin. Once dried (<2mins), it's waterproof.
Don't dip it into hot paraffin if you used PLA, it'll shrink the part and threads won't work anymore

It's compatible with M20/27 connectors for gardening tools (like Gardena) and washing-machine water pipes.

To resist water, UV, mud and kids, it's printed in PETG.

Designed on onshape: https://cad.onshape.com/documents/60f5ce64e1cb45e6997c4387/w/614b02024bce4d4299aa5185/e/118ac1041a1ba00df377b49b