Stone sizes - whet 200mm diam x 41mm x 20mm bore, dry 150mm diam. x 21mm x 12.7mm bore. 275 Watt, 230V motor. Grinding stone rotation speeds -dry 2960rpm whet 135rpm. Combined eye shield / spark arrestors plus wheel guards to protect against flying particles. Adjustable tool rests enable controlled presentation of the workpiece. The ELGI Ultra Dura 1.25 L will be sufficient for a nuclear family consisting of around 2 to 4 members. For larger families, you can choose a grinder of drum capacity 2 L to 2.5 L, such as the Ultra Perfect 2.0 L wet grinder, the Ultra Bigg 2.5 L (Red) wet grinder and the Premium Plus 2Ltr grinder.