These are the RC4WD Magnet Metal Mounts.
FEATURES: Steel construction
For use with the RC4WD Z-B0092 Chevrolet Blazer Hard Body Complete
Set, RC4C3092
INCLUDES: One 2-piece Magnet
SPECS: Outer Diameter: 0.59" (15mm)
Inner Diameter: 0.24" (6mm)
Weight: 0.46oz (13g)