Remo 12 1/2" Nuskyn Crimplock Symmetry Conga Head, M4-1250-N6-D3, size crown: 12,5"; suitable for professional congas, Crimplock world percussion drumheads are Type 4 conga heads, they feature a high collar, glued WatherKing style Nuskyn head with an angled crown and a Crimplock aluminum support rim (flesh hoop), Crimplock is a process that folds the aluminum channel over the top, closing the open channel flesh hoop for added durability.