Abstract: A guide block of the open breach type particularly adapted for use in connection with a vertically disposed cable. The guide block includes two U-shaped hand plates fixed in parallelism relative one to the other, the plates being separated one from the other a distance at least slightly greater than the diameter of the cable. Each hand plate is provided with a hole centrally thereof, and a slot extending from that hole to one edge thereof. The hole diameters are each substantially greater than the cable diameter, and the slot widths are each only slightly greater than the cable diameter. The hand plates are oriented relative one to the other so that the holes are concentrically disposed, and so that the slots face in opposite directions one from the other. The hand plates are fixed relative one to the other so as to define a mouth which provides access to the two slots for a cable.