The Remo Sub Muff'l external bass drumhead system is what you call a drum accessory. It is not an instrument, but a product that helps you create your desired sound. As the product name states, it is an external system, and will have no influence on your sound untill you use the dampening foam inserts.
Free-floating If you do not already have external dampening, the Sub Muff'l can be used on any bass drum head. The external plastic profile is placed on the actual drumhead and between the bass drum hoop without influencing the sound.
The four foam dampening pieces can be used how you see fit. Using only one will already kill a certain amount of sustain. When using all four of them you have a serious increase in attack that makes every sound engineer just that little bit happier working with the sustain level of a bass drum without pillows or blankets in it. Or, metal buckets filled with sand, as Simon Phillips used to do!
Three Sub Muff'l videos Below are three videos featuring the official Remo product videos and the actual presentation at the 2019 NAMM Show. Make sure you are wearing headphones when watching the comparison video.
Remo Sub Muff'l launch at NAMM
Remo External Sub Muff'l Bass Drum System Official Remo product video
Remo Sub Muffl Comparison Video Official Remo product video