Overview Reviews Product Description Medium soft yarn marimba mallet that projects well in the lower half of the instrument. Synthetic core; birch shafts. WARNING: Cancer and Reproductive Harm Product Videos Custom Field Product Reviews (No reviews yet) Write a Review Write a Review × Vic Firth Vic Firth M181 Corpsmaster Keyboard -- Medium Soft – Synthetic Core Rating * Select Rating 1 star (worst) 2 stars 3 stars (average) 4 stars 5 stars (best) Name *Email *Review Subject *Comments