While the contributions of the solo marimba continue to evolve within the world of concert percussion, so do the demands of the mallets that are used by their players. The IP501-IP504 marimba mallets feature large round synthetic cores wrapped with a soft but durable Charcoal synthetic yarn. The core and yarn mix provide a two tone like quality and work perfectly for solo type playing. The IP511-IP514 mallets feature rubber cores wrapped in a light Heather Gray Yarn. The Rubber cores provide you with soft cloud like sounds at the lower dynamics and warm, dark, and rich sounds at higher dynamics. All 8 models are built on polished birch handles and the heavier cores increase projection and enhance the fundamental tone coming out of the marimba.