Optional accessories include platforms, clamps, full and custom spring racks, micro plate holders and additional shelves. Platform holes are drilled to accommodate the different clamps purchased. Spring racks are designed for holding tubes in a horizontal, angled, or upright position. They can also be used to hold flasks up to 1-liter without clamps. The racks consists of a 2-tiered grid of stainless steel springs. The distance between the two grids is adjustable so as to accommodate tubes and flasks of different heights. The spring racks are fastened onto the platform by four screws. Custom spring racks (photo below) allow for a combination of large flasks, microtiter plates and tubes on a given platform.