CHINESTONE have factory producing kinds of Granite and Marble Stone Step/ Tread/ Staricase/ Riser/ Windowsills. etc. 1)Material: Natural Granite and Marble Stone Note: Some customer require the top surface of step with anti-slip lines (flamed or sandblasted) Risers: Standard Size: 110/120/130/140/150 x 14 / 15 x 2 cm, top polished only Windowsills: 120/150/180/220x30/35x3cm/4cm,etc. as per customized sizes. http://www.chinestone.com/