This upgrade spring and barrel can fit for both LN mk3 and dart zone pro series mk2 nerf gun blaster.

Material: copper for the barrel.

Piano wire for the spring.

Spring power: 12kg.

Barrel length: 83mm; 105mm; 120mm; 140mm.

Inner dia: 13mm.

Outer dia: 16mm.

Package: 1x mk2 barrel.

or 1x dart zone mk2 spring.

Note: the inner dia of two outlet parts need to be widened to 16mm for installing the extension barrel