Hard plastic material with a checkerplate finish - the tiles are about 500mm square and interlock, with tapered edges to avoid tripping. At the moment I don't have enough for the whole floor - I got them when the bike shop I managed closed, they were just in the workshop area. When I get round to it I'll get some more and finish the workshop. Surface is pretty much non-slip and seems to cope with spillages etc.
Workshop is part woodwork and part for my bicycle repair/servicing business which tends to have degreasers and oil dripping onto the floor (I have a large, disposable, sheet of corrugated cardboard under the bike workstand)