some colors are a bit harder to melt but overall, they work fine with the 3d pen (no name) that I got.

I do not recommend it for beginners. If you sit down and experiment with temperatures, you will get a good print, but it is not the best material. It also seems to not adhere well with other PLA.

I bought them because I wanted to print some small things in different colors on a 3D Printer, and although they are for a 3D pen, the diameter and material are compatible with a printer. As for their use for a 3D printer (which is not recommended by the manufacturer), I have to say that it is not impossible, but it is certainly quite difficult to find the exact settings for the bed and temperatures. And until you find them, you will have wasted half of a color, so if you don't know your printer very well, it's better not to try them on a 3D printer because even from color to color they have differences in bed adhesion, retraction, temperatures, etc. Otherwise, some of the colors (e.g. pink and orange) produce very nice results. Some others (e.g. yellow) are terrible as materials

I don't understand why some pieces have 3 threads and cost 8 euros, while these ones have 10 threads and cost 3 euros.

Attention, it is for a 3D pen. In 3D printers, even though it is the same material and diameter, it has problems sticking to the table. It's difficult to describe their difference exactly. However, in my printer prints, it would come off the table, even with the glue I tried. I changed the filament and the print came out perfectly on the first try.