Abstract: This invention provides a unique utility knife, which has at least two extendable and retractable parallel blades. The blades are easily operated with one hand by a mechanism on a non-force-bearing surface of the knife. The blade handle of this utility knife may be bent to enhance the ergonomic ease of use of the knife. As a result, the utility knife is efficient, as well as safe, convenient and economical.

Abstract: A sealing plug for a cone-type tie rod opening in concrete walls and the like formed by solid high density polyvinyl chloride of generally conical shape having a cylindrical head of diameter somewhat smaller than the mouth of the opening to permit insertion therein of the plug and provided with a peripheral front planar flexible lip of diameter slightly greater than said diameter of the head, the head tapering into a rear frusto-conical plug section, the overall length of the plug being small compared to said head diameter, such that the forcing of said plug into said opening causes the side walls of said head and at least part of said rear plug section to pressure-seal with adjacent concrete wall portions of said opening and with said lip resiliently pressed forward to effect a front peripheral seal. The plug may also be adapted with roughened side walls to intermix with concrete particles during plug insertion to lock the plug in the opening against withdrawal.