It's standard US bathroom sink with 1-5/8"to 1-3/4 inch drain hole(40-60mm).
Simply take the strainer out, the bathroom sink strainer has a simple load-off design, easy to daily clean
Pop Up Drain Stopper Built-in Anti-Clogging Strainer With Overflow
This drain stopper has a anti-clogging basket strainer inside that neatly collecting hairs and prevents the drain from clogging up,stuff will not get into the drain, such as jewelry, ring, dirt and so on.
How to choose correct pop up drain
The is pop up drain with overflow built-in anti-clogging strainer
The overflow pop up drain fit sink has spillway hole
If your sink has no spillway hole,please choose pop up drain without overflow:B07WNP1FPQ
NOTE:Please confirm before buy whether the basin with spillway hole