[Tango-L] temporary dance floor

[Kace]

Hi List,

While looking over the photos of the World Tango Dancing Championship,
I realised the organiser frequently create temporary dance floors
out of slabs of tiles (see photos):

 http://www.mundialdetango.gov.ar/fotos_2005/clases_rural_2.jpg
 http://www.mundialdetango.gov.ar/galeria_fotos_detalle.php?id=23

Can anyone tell me what material are these?  If you have had a chance to
dance on them (during the festival's milonga or class), what is your opinion
about it?  Also what is the average dimension of such a dance floor?

kace
tangosingapore.com