The grinding discs different grinding surface

The 2 grinding discs in the photo is the same composition but with totally different grinding surface.  Both grinding discs with 3 reinforce net and one black paper coated on grinding surface for make maximum safety performance. Do you know why they have totally different grinding surface? 

The answer is we using different mould. A disc using rigid moulds and B disc  using rubber moulds , you can see the B disc black paper insert and bonded tightly  with the reinforce net and abrasives oxide. This will make the grinding disc with more sharp and fast grinding ability especially at beginning of grinding works.  The A disc advantage is the black paper can protect the reinforce net well especially when heavy grinding applications. 

Both of these two style grinding discs welcome in different market and we will choose what type moulds will used according to customers request.