Abstract: Flooring blocks which can be easily joined to each other and removed have a square-shaped main body and have, on the sides of a square-shaped main body, concave portions and convex portions. In the block main body, block main body side pin insertion paths are perforated along the sides on which the concave portions are formed, and in the convex portions, convex portion side pin insertion paths are perforated. In the block main body side pin insertion paths, pin main bodies of lock pins are inserted slidably between joining positions and housed positions, and the block main body side pin insertion path is partially formed into an open groove opened to the block main body surface, and the open groove is provided with a first lateral groove and a second lateral groove, and block main bodies adjacent to each other are joined to each other by sliding the pin main body of the lock pin in a state that the concave portion and the convex portion are engaged with each other.

Abstract: A receiver apparatus includes a display apparatus for displaying signal strengths of signals of a plurality of reception frequencies. In the receiver apparatus, a receiver circuit of one system receives a high-frequency signal having a predetermined reception frequency, and a detection storage circuit detects and stores the signal strengths of the signals having a plurality of reception frequencies received by the receiver circuit by selectively switching over among the reception frequencies of the receiver circuit according to a predetermined order of the switching. The display apparatus has a plurality of display sections, and displays on the plurality of display sections the signal strengths of the signals having a plurality of reception frequencies stored in the detection storage circuit according to the order of the switching. Further, a demodulator circuit demodulates a high-frequency signal having at least one reception frequency received by the receiver circuit.

Abstract: A ladder wherein a plurality of rounds are pivotally and turnably mounted to and between the right stanchion and the left stanchion at proper spaces, and supporting arm levers are detachably fixed from both stanchions to the round by bolts or machine screws.