Promark Jim Wunderlich JW4 "System Blue" Medium Hard Marimba Mallet. The JW4 speaks well in the mid to high range of the marimba, yet retains the warm, rich sound of this series of mallets. Length: 17" Head Size: 1.4 x 1.70". The JW4 features a rubber-like synthetic core wrapped tightly with durable synthetic yarn on a lacquered birch shaft for a smooth finish with maximum strength. Durable enough for outdoor environments, but the lush tone of these mallets is an appropriate and tasteful choice for indoor concert or marching settings. All Promark drumsticks are designed and manufactured in the USA to the most stringent quality controls in the industry.