... are available in four sizes 14x14cm , 18 x 18cm ,23 x23 cm, and 28 x 28cm , units all have simple analogue control ... Uniformity . d.Available in four sizes ,14 x14 cm , 18 x 18cm ,23 x 23 cm,28 x28cm as well as multiposional hotplate .e ... Hotplate Main parameter Standard Outfits Clip Removable Holder 28 x28 cm ceramic surface small Digital Laboratory heating plates