This is a protractor that can measure internal angles and requires four sets of M4 × 12 screws, M4 nuts, and washers for assembly.
这是一个量角器,可以测量内角,需要四套M4×12螺钉、M4螺母和垫圈进行组装。
我稍微改变了量角器的锁定部分,使螺钉更牢固地固定。
I slightly changed the locking part of the protractor to make the screws more securely fastened.