ok, now i am totally confused, hopefully some of you baca experts can straighten me out: am going to buy this bag, but i am confused on the sizes. there are two sizes right? depending on which website, i am getting really different measurements. example: revolve has the large at: 18x11 and the smaller one at: 15x9.5 shop bop: large-24x18 small-18x11 and active end. large-22x13 small -17 x10. now i know these bags are hard to measure but i need the largest one....can anyone help me with this? thanks so much!!