You can't go wrong with PLA for a 0.4 mm, but another filament, like carbon fiber for a 3D printer, works well with a nozzle in the 0.4 mm to 0.6 mm range. When it comes to buying filaments, trust is key. Choose a reputable brand like Filamatrix for expert guidance on each filament's performance.

The standard Ender 3 nozzle size is 0.4 mm in diameter, which is the most common size and suitable for a range of prints. Small diameters create thinner lines of filament (better resolution) at the expense of printing speed, while large diameters can push out more filament at a time at the expense of detail.

Some manufacturers like e3D Have special markings on the side that indicates what diameter you have. e3D V6 have 6 sides, and the amount of indentations explains it's geometry. 3 dots is a 0,4mm nozzle. While 4 dots is a 0,6mm nozzle.