Small magnetic big impact

I got myself this magnet for a specific purpose; to fix the fuel filler flap of my car. I always had the problem that my tank flap always opened while driving. Since I have only tried a Velcro, which has just held for 2 days I came to fix it with magnets the idea. Now I've been driving around three months with my car and still keep all the magnets. Do not drop out, but keep firmly on the car bombs and the tank lid and still I get the fuel filler flap on. I was initially very skeptical about whether such small magnets can hold at all. But they convinced me to the complete satisfaction and it was also the cheapest option for me.