Ive looked at the LN one and the magnet doesnt look all that large.....
I was considering this one with a XL magnet, what do you think?
http://shop.ebay.com/?_from=R40&_trksid=p3984.m570.l1312&_nkw=m12+1.25+magnetic&_sacat=See-All-Categories
Its the one last on the list
and I think the correct size is m18-1.50 on the boxster