Tested and in fine working condition. (https://www.glascol.com/GlasColItem.aspx?Item=100A+O408)

Glas-Col 1L Heating Mantle, model 0408, designed to meet your laboratory's temperature control needs. With a  1000 mL capacity, this mantle is ideal for various scientific applications requiring consistent heat.  Please note that the control is not included with this purchase.