This design is proprietary to Freer Percussion and took nearly three years to develop.  Every timpani player requires a double ended mallet at some point whether it be for Carter March, Don Juan or even Enigma variations and flipping a stick over from end to end can often result in disasters.  It may look theatrical if it’s executed well but one always has to consider sound first.  Everyone knows butt ends will only damage the heads especially if using calf and often proper double ended mallets don’t always respond and get off the head well.  This mallet solves all of these issues at once.  Simply turn the mallet head to the other side and you get the desired effect faster and more safely than ever.  My former model of this mallet featured some adhesive felt which was just OK but had a bit of slap to the sound and was not an easy thing to replace.  This core is easy to recover if you wear out the felt side and will absolutely last a lifetime if cared for properly.  Cores can also be used on other threaded shafts by many manufacturers but are not sold separately at this time.