It is essentially a perk for investing in a PP....it guarantees you opportunity to purchase more shares at a guaranteed price within a time period.  If the sp soars then you are able to use your warrants to buy more shares at the presumably lower guaranteed price...I participated in the PP because I want the warrants and am optimistic I will want to exercise them at some point....if this thing gets to a buck +, who wouldn't want to be able to buy more at 15 cents