Moongel is a translucent blue, sticky, gel-like substance produced by the drum practice products company RTOM.
It has been incorporated into several products and come in packs of four or six which can applied to a drumhead or cymbal to diminish the higher overtones.
It also has become a popular studio technique due to its damping properties.
The manufacturer claims that unlike most practice pads they allow no "free rebounds", which is said to accelerate muscle development.
Moongels are made from 53% PVC copolymer resin, 27% Dioctyl Terephthalate, 2.5% Epoxied Soybean Oil, 3% Calcium-Zinc Stabilizers, 7% PVC-based Thixotrope and 7.5% Adipate Plasticizer-based Thixotrope.