Polymeric compositions of matter are described comprising olefin polymer chains having Mn of about 400 to 75,000, a ratio of vinyl groups to total olefin groups according to the formula 1 vinyl null null null groups olefin null null null groups null [ comonomer null null null mole null null null percentage + 0.1 ] a null 10 a null b ( 1 ) where, anullnull0.24 and bnull0.8, and where the total number of vinyl groups per 1000 carbon atoms is greater than or equal to 8000nullMn. The invention includes a method for preparing these polymeric products comprising contacting one or more olefin comonomers with a catalyst system containing a transition metal catalyst compound and an alumoxane wherein the aluminum to transition metal ratio is from 10:1 to less than or equal to 220:1 (AL:Me). The process conditions of the invention permit predictable macromer characteristics of both molecular weight and vinyl unsaturation.