FLAT-TOP AND UPSTAND TRAY DIFFERENCES Unlike on the continent, many British bathrooms are not completely 'wet' areas. A shower tray with an integral tiling upstand provides a raised lip to be tiled against. A flat top tray does not include this raised lip, but are far more common. Features and Benefits - Easy to fit - The Pearlstone Matrix has screw retention so that the feet from the leg set (sold separately) can be screwed directly into the base of the tray - All trays have a flat underside making installation and levelling even easier - Slimline - At just 40-45mm high Pearlstone trays are amongst the sleekest on the market - Perfect for a modern and contemporary wetroom design - Patented Technology - Made of the patented 'Pearlstone Matrix' making the range one of the.