Compass+Ruler / Compass

Compass is an essential study appliance and office appliance. However, the recent compass has some problems during the process of the use, for example, determination of drawing circular and arc radius using tools such as ruler, the requirement of refine at each time of drawing. This is not convenient. Compass + ruler is a compass with the ruler. While needing to draw the circle or arc, only place the vertical ruler into the horizontal state. Directly according to red marked mainline corresponding length, accurately draw the needed circular shape and arc. This could satisfy the needs of varieties of study and office.