ok got my order from parts express, took about 10 days, the magnets wernt packed to well so some of the edges were a bit chipped. anyway they sent me the 65mm ones i ordered but the 60mm ones ended up 75mm? so checked there site and the code on the packing matches, so i dont know why there description says 60mm. my next issue is there effectivness, the 65mm wernt bad but the 75mm almost did the trick, trouble is my driver magnets are 70mm and i read somewhere they should be 1/2 to 2/3 of the driver size. so why is it the 65mm ones dont do the job as well as the 75mm ones? would it be better to use the 65mm ones and a steel cup, as im worried im swamping the driver magnets with the 75mm units.