Matt ball:Skin-friction force:2.5,2.8,3.0,3.2,4.0.Diameter:2.0-12.7mm. Matt ball:Skin-friction force:2.5,2.8,3.0,3.2,4.0.Diameter:2.0-12.7mm.The matt ball widely applies in stainless steel bar buckle.With great pulling force, high intensity, rust prevention.Nonstandard orders customized are available.