Perpendicular height/distance measuring tool for Do It Yourself and General Construction Works, uses Pythagorean sum of squares principle for measuring height and distance with three point reference line

摘要

A right angled circular sector casing (20) contains winder (21) on which is wound flexible non elastic line (40) fitted with three small diameter different colored retaining rings (22) at three preset places from the end of the line and with at least three fixings designed to support the rings. The fixings are headless nails or pins with a similar diameter to that of the rings. The housing has a hole at the top of the right angle so that it can be held in placed by a fixing.