Abstract: A rack for keys and small articles has multiple split rings to receive and carry such items. The rings are held by a support with feet and a handle. By providing two rows of five rings, keys may be classified and stored on a decimal basis, that cross-references to the last digit of an auto license plate.

Abstract: A transmission-type electro-acoustic delay line comprises an acoustic medium delimited by a cylindrical lateral surface, a plane terminal surface on which are fixed two symmetrical transducers, and a focusing terminal surface in the form of a spherical cap. The angle formed by the plane surface and the axis of revolution of the spherical cap is less than 90.degree. by an angle such that the incident acoustic wave undergoes a single reflection on the focusing cap and such that the reflected acoustic wave is concentrated at the level of the output transducer.