Whiteboard erasers

[BresciaBike]

Are they just a foam or plastic handle with felt on the other side? I know damp tissue can be used too. The proper erasers, however, are they just plain felt?

Thank you for answering my most random question on a Monday afternoon.

At our school, the big classroom whiteboard erasers are the felt/handle type. But the little individual whiteboard erasers are a very firm, compacted foam.

I'm most intrigued!