MLB Mini Batters Helmet. Mini helmet is a perfect major league baseball batting helmet for autographs and collectors. The Mini Replica helmet comes with Official MLB team decals and great graphics. ABS plastic mini batters helmet shell comes with display stand. MLB helmet size is 6.75"(L) x 4.5"(W) x 5.25"(H) – 12 scale versions of MLB baseball helmets. MLB Mini Helmet ships by USPS or UPS.