http://www.amazon.co.uk/Quality-USB-Optical-Scroll-1600DPI/dp/B003E2X9E0/ref=pd_ts_zgc_computers_430567031_5?ie=UTF8&s=computers&pf_rd_p=294457107&pf_rd_s=right-9&pf_rd_t=101&pf_rd_i=350613011&pf_rd_m=A3P5ROKL5A1OLE&pf_rd_r=1NKKAZ27DCQYT2ERYECZ