Correct

扣紧

/ kòu jǐn / 
Strokes

Example

As a Verb

fasten; secure; bind

1
Kòu
扣
jǐn
紧
luómǔ
螺母

binding/securing nut

2
Kòu
扣
jǐn
紧
luógǎn
螺杆

fastening bolt