Neodymium magnets are the strongest magnets known to man – definitely strong enough to hold the axles of your magnetic mousetrap vehicle. Each magnet measures 1/4" x 1/4" and is nickel plated with the poles on the flat ends.
Caution: Always keep magnets away from computer equipment, 3.5" disks, credit cards, and windup watches. Magnets might be harmful if swallowed.