Holds 18 hydrometers in vertical position The middle and top plates have 25mm (1 in.) diameter holes, bottom plate wells taper from 25mm to 9mm to hold the hydrometer bulb securely Extended base measures 21 x 21.6cm for tip-proof stability Overall height: 25.1cm with handles for easy transport Rugged polypropylene construction, steam autoclavable at 121°C (250°F)