Slotted tungsten beads for jig hooks and Euro rigs. The slot is cut to seat clean against a 60 or 90 degree bend, so the bead sits square and the fly rides true.
95% tungsten alloy, about 18 g/cm³, roughly 1.6 times the density of lead. Sizes run 1.5mm to 4.5mm. Solid finishes come in 23 colors, speckled in 11 colorways. A 2.5mm bead seats the same way this season as it did last, which is what lets you dial a sink rate instead of guessing at one.
Slot size matters more than diameter. A slotted bead will seat on a jig hook that a round bead of the same diameter will never clear. At the top end, 4.5mm caps out around a #4 and will not fit larger hooks.