A drywall anchor installation device comprising, inter alia, a main driver member configured to engage a Philips head screw top, a plunger member configured to engage a Philips head screw top, and a plunger member guiding mechanism including a compression spring and a guide pin. 8, and said first component having a molecular weight such that the viscosity of the solution is less than about 50 mPas; and a method of prophylactic treatment of teats of lactating mammals. In the plural data lines, the plural accumulating portions are respectively connected individually via switching elements. The third lens has a positive curvature radius on the object side and a negative curvature radius on the image plane side. The receiver estimates the symbol timing offset based of a block of received symbols based on a cyclic prefix and suffix. The method includes grouping the physical erasing units into at least a data area, a backup area and a spare area; and setting a value obtained by summing a minimum threshold and a predetermined number as a garbage collecting threshold.