Size is 31mm (width) by 178mm (length) Comes out to 1.2inch width x 7inch length This will fit a 35x198mm Mock suppressor perfectly. Comes pre-installed with the Spring & SEVEN Foam Discs. The entire spring is covered If your mock suppressor is shorter than this, you can cut the internal spring to your mock suppressor length & just add the foam discs. If it's wider, you can wrap this in some paper or bubble wrap to make up the space inside your mock suppressor & make sure it's a snug fit! Make the pew pew noise go bye bye!