Radius Marker, Mini, 8 in Radius ORS NASCO strain on neck muscles and strain on neck muscles and improves productivity Absorptive protection is engineered into the window Not surface coated so the window will not lose its protective qualities HVAC installers Precision tools made of rust proof aluminum and anodized for lasting protection The arms are precisely aligned with spring tension joints to guarantee accuracy and rigidity The holder accommodates flat or round soapstone and pencils All are a folding type design the three smaller models will fit conveniently into a shirt pocket All have sturdy friction joints to maintain rigidity and accuracy