Super Duo Beads are a Czech made, glass Two Hole Seed bead manufactured by Matubo company from Czech Republic.  They feature a unique oval shape and two stringing holes. Much like an inverted hourglass, tapering at the ends and widening in the middle.
 
Measures: 2.5x5mm, with two .8mm holes 
Color: Jet Rainbow Iris (DU0523980-21405)
Sold in packages of 10 & 22.5 grams