Abstract: A hands free square and level which includes a self holding square that has central channels formed by opposing inner and outer walls. The central channels include mounting holes in its outer wall to allow it to be mounted on a work piece via screws. An inner wall, opposing the outer wall, has corresponding screw driver apertures to allow access to the screws by a screwdriver. The central channel also has transverse bolt apertures which allow the square to be face mounted on a work surface by inserting a bolt through a transverse bolt aperture and then into a work surface. A separate detachable level is sized to slidably fit within a central channel. Hands free operation is achieved by attaching the self holding square to a work surface and then inserting the level into a central channel. An alternative embodiment uses one or more levels which are integrally mounted on the square.

Abstract: A bacteria filter has a base member with an open circular groove in which an adhesive bonding material anchors one end of a generally cylindrical filter element. The filter element has longitudinally extending pleats and the opposite end of the filter is adhesively secured in an open circular channel in an end cap element opposing the base member. A housing for the filter is sealed to the base member in spaced surrounding relationship with the filter element and has an inlet passage therethrough whereby air may enter the filter device through the inlet passage, flow through the filter element, and be emitted through the outlet passage in the base member. The method of assembling the filter device includes a unique method of retaining the pleated filter element in the desired cylindrical form while bonding the filter element to the base member and/or end cap.

Abstract: A bacteria filter includes a pair of generally conical housing sections having confronting marginal flanges adapted to be welded together to seal the sections into an integral filter housing. The flanges have a pair of tongue-in-groove connectors to facilitate alignment of the sections during assembly and to automatically stretch a filter element between the two sections during assembly to optimize the filtering capacity of the filter. Each section of the filter device has a co-axial tubular neck extension defining an inlet and outlet of the filter device.