Rubber bellows - KNOTT KF27-KF35 protective rubber. Original product of the brand: KNOTT. Protective rubber for installation on KNOTT KF27-KF35 overrun devices. The rubber bellows is a simple solution that protects the bolt carrier against water and dirt ingress. Thanks to this protection, there is much less need to replace the bolt carrier or sliding sleeves.
Dimensions: length 150 mm, hole diameter: 55 mm.