Radio Room Wall Clock -- Decorative Vintage Maritime Timepiece
In the olden days of maritime wireless communications, every radio room had one of these -- a clock with the special markings to assist wireless operators with their important mission for the safety of passengers, crew and cargo. It is a must for every vintage radio room and adds authenticity to it for those "in the know" -- and with an LI of just 0.75 (which gets rounded to a straight 1) there is room for it on the smallest parcel.
The red wedges indicate the silence periods for 500kc, the green ones for 2182kc. During these, all traffic would seize and radio operators all over the world would listen for distress calls.
The red markings around the border were used to time the auto alarm signal that was sent preceding a distress call according to ITU regulations -- 4 seconds on, 1 second off, repeated a dozen times.
If you are interested in details, have a look at http://jproc.ca/radiostor/cw500pt1.html -- it is an excellent description of maritime communication in bygone days.