Shields and seals are protective closures which retain lubricants and assist in preventing contaminants from reaching internal surfaces. In torque-sensitive applications, it may be advantageous to use shield rather than seals because there are no contacting surfaces to create drag.

Metal shield--- ZZ ---- With Snap Ring

Non-Contact shield retained in outer ring,Low ingress of contaminants.Mainly used for miniature ball bearings or Thin Ball Bearing.

Most sizes are available with metal shileds, Shields are designed to prevent larger particles from entering the bearing and also to keep grease inside the bearing. They are secured in the outer rings with a steel snap rings. These are removable shields.As the shields make no contact with the inner ring, they do not increase starting or running torque. Shields on miniature bearings are generally made from  SPCC,1Cr18Ni9  stainless steel.

Metal shield--- ZZ ---- Without Snap Ring

Non-Contact shield pressed into outer ring.In order to reduce lubricant leakage and keep low ingress of contaminants.This shield design do not increase torque. These are non-removable shields. Mainly used for deep groove ball bearing( Bore>12.00 mm).Shields on deep groove ball bearings are generally made from  SPCC plate.

Rubber seal----RS---- little contact inner ring.

Rubber seal pressed into outer ring, and provide a little contact into the innner rings.

It provide an effective seal against very smaller particles such as dust and moisture while preventing lubricant leakage. Contact seals produce much higher frictional torque levels than shields and reduce the maximum speed of a bearing.But it greatly increase bearing torqure. 

This seal are consists of Nitrible Rubber bonded to a metal washers.This design can be used for most of deep groove ball bearings including miniature bearings(Bore < 12.00mm)

Teflon seal ----TS --- little contact inner and outer rings.

The inner lip of the seal rubs against the bearing inner ring to provide an effective seal against smaller particles such as dust and moisture while preventing lubricant leakage. Contact seals produce much higher frictional torque levels than shields and reduce the maximum speed of a bearing.

This seal are made from teflon seal with glass fibre-reinfored. Manly used for miniature ball bearings.

Seal can flex to accommodate internal pressure changes.

Best protection against contamination and reduced lubricant leakage. However it is very low speed.