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From what I have since found out though, diddly, they’re for stepping out of the shower on to, instead of a bathmat, not for in the shower tray, as I originally thought.
I would think a duck board would be more unsafe to be honest, shower trays more often than not have non slip surfaces.
I agree about wooden chopping boards, this rental has glass ones. In fact the whole place is immaculate, thankfully, you never quite know what you’re going to be faced with do you?