The Andrew Markworth AM4 marching keyboard mallets feature hard 1 1/4 weighted round cores wrapped in a blended yarn on a birch shafts. These mallets are ideal for the upper register of the marimba. All mallets in the Andrew Markworth signature series were built using Promark s proprietary new mallet technology. Rather than purchasing off the shelf parts and utilizing outdated manufacturing practices all cores are injection molded in house and threaded onto shafts using our patented insert design for unprecedented consistency and durability. In final assembly all Promark mallets are wrapped using a state of the art winding machine developed from the propreitary winding technology of the world s premier guitar string manufacturer. This mallet series features a variety of core shapes hardnesses and materials to accommodate the needs of the competitive marching percussionist.