Bolts and screw heads
The long bolt in the picture has a thread at one end and a screw head at the other end. When in use, screw the thread into the designated hole of the furniture, and insert the exposed part of the bolt into the designated hole of another furniture, that is, a part of the furniture is spliced together, but it is loose and not yet fastened.
Use of metal parts
At this time, the bolt head is exposed in the reserved hole of the furniture. Press the cross-faced part with a notch at the bottom of the circular metal on the bolt head, and the circular metal is just flush with the furniture. Then tighten the circular metal sheet clockwise with a cross screwdriver to lock the bolt head. These two metal sheets also fix a certain part of the wooden furniture.
Matters needing attention
This practice is very popular in Europe and America, but only if there is an embedded graph, otherwise nothing will happen.