Correct

内螺纹

/ nèi luówén / 
Strokes

Example

As a Noun

internal screw; internal screw thread

1
Nèi
内
luówén
螺纹
móchuáng
磨床

internal thread grinding machine

2
Nèi
内
luówén
螺纹
kǎchǐ
卡尺

thread inside callipers