Most of the flex magnetic strips I’ve seen are magnetized N-S-N-S-N-S per given length and side. You would need a magnetizer capable of remagnetizing it so one side is South and the reverse side is North. I have seen pickups made with flexible magnet strips and many early Sears Silvertone guitars, for example, used a flexible magnet material inside the pickup. Flexible magnet strips also appeared on the bottom of some Rickenbacker guitar and bass pickups. It works rather well but you need to specify to the vendor your particular needs and applications and magnetic orientation.