Sinsemillia means 'without seed', it is the technique that nearly all growers use. It basically means removing all male plants from the crop so the females remain fertisied. This means they put all their energy in to resin production (thc) and not producing seeds. The most potent strain I have smoked is probably a variety of white widdow I got in amsterdam called white widdow maker. Was insane was high for hours and hours off half a joint. I wasn't a very experienced smoker at the time though so can't compare it to what I am smoking now.