If you use over 0.25g BBs we recommend this type. 

The Namazu comes with a stainless steel pin that fills the center hole in the Namazu. This prevents the Namazu from compressing when the hop is turned up for heavier bbs. 

Forget about having to turn your bucking inside out and filing it down, or cutting into your inner barrel. Get flat hop system results to distance and accuracy with the least amount of hassle possible. We use the Namazu in all our custom shop work! 

ORGA Magnus barrels are made with the Namazu hop in mind. The extra hop bucking groove along the left hand side of the Magnus barrel allows the hop bucking to be easily rotated 90 degrees, making it quick and simple to install the Namazu hop‐up. 

https://www.youtube.com/watch?v=5gyGhmIU3js