The Maestro Jeffrey de Zwaan 90% from UNICORN is a dart set with barrels of 90% Tungsten and is the official competition darts of Unicorn dart player Jeffrey de Zwaan. Jeffrey de Zwaan throws a straight phantom grip dart, these darts have a laser engraving of a cobra. This set comes in 2 weights; 23-25 grams. 23G = Barrel Length: 50.80mm, Barrel Width 6.70mm. 25G = Barrel Length: 50.80mm, Barrel Width 7.00mm.