citrate"n/m here is wher ei got mine

www.herbaladvisor.com goto brand NOW then to the apha index
forM an dlook up magnesium citrate, (or after searching for NOW brand, youcan also then put in search on that web/brand for magnesium citrate.
mine is 250 caps / at 200 mgs each for 7-8 $ so that woudl las tyou quite a while..
i have heard also that soem have used magnesium chloride also.