The 3B  nozzle types are provided with extra-long tip and the heater is far from the injection point, allowing less heating of the gate area. In this way it is possible to improve cooling in the gate area and in the contact zone between the pin and the plastics. As consequence the aesthetical defects due to the excessive heating of the thin wall and the plastics glueing around the pin, are eliminated. 
Therefore the 3B types (F or  DN)  are suggested for injection moulding of thin wall parts, with fast cycles.

The 3B types are to be used with shut off valves, therefore it is suitable for the sequential control  injection. This allows to regulate the plastic flow at the best rate, in special applications, such as containers that cannot be injected externally, due to the presence of the label. Moreover the shut off injection nozzles leave a very clean injection point, that is quite invisible and free from imperfections or material threads that could affect the content.

Moreover we remember that the thin wall applications require high pressures and it is important to avoid pressure lacks, by using nozzles with diameters wider than required for the injected material volume (even for low volumes, use 30 or 32 diameter).