The present invention relates to an uracil compound of the formula I: . The invention has particular application in the alignment of slave clocks to a master clock. The metallic cover has a main portion, a locking portion and a resilient portion. The distal end of each appendage projects beyond a rear face of, respectively, the molding or glazing delimiting the hole, and the distal end of each appendage is deformed by temporary softening, for example through application of ultrasound, to come into contact with the rear face of the molding or glazing at the periphery of the hole or around the entire periphery of the hole. 7; a marking agent; and 10 to 45% propellant. The PIFA further may have another radiator, which resonates in the upper operation band.