It's usually put on the feet of furniture, mainly fouction of height adjustment. Screw section is made out of steel, base sectiob is made out of plastic, various base shapes are available.
1. M4-0.7.
2. M5-0.8.
3. M6-1.0.
4. M8-1.25.
5. M10-1.5.
6. M12-1.75.