Mathews Inc. manufacture archery bows and accessories. One of their products is a Mathews Harmonic Damper, a device which dampens the vibration in the bow after the arrow has been fired. It is essentially a dumpbell shaped weight enclosed in a rubber. The weight can bounce around soaking up vibration. Mossberg have scaled the Mathews Damper up and installed it in a Mossberg 835 Ulti-Mag stock. The theory is that this will dampen perceived recoil in a 3.5″ Ultra Magnum 12 Gauge Shotgun in the same way it dampens vibrations in a bow. I guess we will find out when they start shipping it.