New magnets for buy, need help

[cenizasblancas]

Hi, i´m going to buy magnet from Shea from magnetic holds and i need help because i going to buy neodimum magnets for magnetize magnets and ceramic for desmagnetize, my question is because Terry said in a previous post that he uses 2 rectangular ceramic magnets for desmagnetize, one face up N the other face up south, i need to know if this method is usefull with bar magnets.
In the list that Shea they have a Ceramic 5 magnet in this size 0.125T X 0.5W X 3.25L, can i use it for a 7 string pickups?

Thanks for your great help!!!

Juan