Oxballs Masterjack Double Penetration Stroker - Jo Black Ice - Blue Ox Designs Llc Dba Oxballs. Heavy, fleshy MASTERJACK is for pro-level gooners, stroker that crave something thick with two hole they can fuck with hard. It's hefty, feels blubbery in your fist and packed with features that'll make your JO so much better than a basic handy.MASTERJACK has a handle so no matter how greasy sloppy and wet you bate, it stays in your fist. It's made of our softest silicone blend flubbery Plus+SILICONE with a dull suede finish and industrial diamond plate grips all over the outside.You can fuck it 2-ways: One end has a tighter butt-pucker hole with inner ribs and nubs to add feel to your shaft or flip it over and slide into the ringed sloppier hole a bigger gape for a smoother jack.