此款極座標式求積儀是由 Lyth Instrumentfabriks AB在瑞典製造銷售，型號為 7513。這款求積儀搭配一組縮放儀連桿，固定桿與中間的追蹤桿長度是可以調整的，這樣的設計可以應付大面積和小面積區域的量測。求積儀中有一根細針在導螺桿上移動，以記錄紀錄輪的轉動圈數。細針裝有一個特殊按鈕，壓下後紀錄輪會自動歸零。

This polar planimeter was manufactured and sold by Lyth Instrumentfabriks AB in Sweden, model No. 7513. The planimeter is equipped with a pantograph linkage, and both the fixed rod and the central tracing arm are adjustable in length. This design allows for measurements of both large and small areas. Inside the planimeter, a fine needle moves along a leadscrew to record the number of revolutions of the recording wheel. The needle is fitted with a special button that, when pressed, automatically resets the recording wheel.