The DM/PM "Top Hat Mod" Spacers work on any model Dye Matrix or Proto Matrix Markers. They are designed to work with any bolt system. Whether you are using a stock bolt in your DM or PM marker, or you upgraded to the L7 bolt, this kit is a must have. TechT designed the spacers to give you maximum control over your marker's operating pressure. Using more spacers increases your marker's operating pressure which allows for lower dwell settings and better air efficiency. Just another nice, little way to fine tune your marker to your playing style and needs. As you can see, the spacers are form fitting to the back cap. They take up as much room as possible for any bolt model. This maximizes adjustability. You just take a razor and cut the spacers to best fit your bolt system. The tail spacer is made up of two spacers halves that are held together by an o-ring.