Tila beads are 5mm flat squares, 1.9mm deep, drilled with two parallel holes 0.8mm in diameter. The bead has one flat side and one slightly raised in the centre so it can catch the light.
They are prone to cracking and chipping so care must be taken when handling. Always use a bead mat or other soft surface.
Tila beads are sold in grip seal bags of 10 grams. There are approximately 120 beads in a bag depending on the finish.