Abstract: An improved spa nozzle that is capable of entraining high air flow rates from the surrounding environment, said nozzle of the type having a water input conduit of diameter D, a flow output conduit having entry and diameter of DID, a transition conduit having a diameter of ID and a length of PL, and an air entrainment conduit, and wherein the following ratios are defined to describe the relative geometry of the nozzle: ?=PL/(DID?ID), ?=DID/ID and ?=D/ID, the improvement comprising: the water input, transition and output conduits being configured such that ? is in the range of 1.3-5 and ? is>1.9.

Abstract: A compact audio reproduction system for two input signals includes at least four loudspeakers disposed at the vertices of a quadrilateral not more than two feet on any side and such that no two loudspeakers are located at a distance from one another which is less than one-fourth the greatest distance between any two loudspeakers. The two input signals are connected to alternate speakers such that no two loudspeakers at adjacent vertices of the quadrilateral produce the same signal such that a listener at an arbitrary location perceives a sound source larger than the quadrilateral and significant stereo image. The signals received by two loudspeakers located at adjacent vertices may receive signals which are equalized separately from the signals received by the other loudspeakers for the purpose of reducing comb filtering and improving the tolerance of the device to placement near walls and other obstructions.

Abstract: A rugged adjustable, optical alignment system is well suited for use in low light environments or at night. A rear sight includes a U-shaped array of, preferably, first second and third substantially cylindrical, transparent, tritium vials arranged such that the elongated cylindrical side surfaces of the vials are exposed to define an array of elongated illuminated segments. The array is preferably in the shape of a “U” having a first horizontally aligned vial positioned below a sight notch with a second vertical vial positioned above and to the left of the notch. A third vertical vial is positioned to the right of the sighting notch, above the first vial. In use, a front blade or front post also containing a tritium insert is aligned within the rear sight's U-shaped array of illuminated segments, thereby providing an intuitive sight picture.

Abstract: A removable optical sight mount adapted for use with a military-style rifle such as an M1A provides a centrally aligned support projecting well to the rear for use with sights having very limited eye relief. The removable sight advantageously uses a three point lock up or attachment to the rifle, the three points being (1) an elongated longitudinal tenon engaging a groove on the left side of the rifle secured with a fastener and cammed into tight engagement with the groove, (2) a transverse rear guide block, and (3) an adjustable front set screw that, when tightened, bears on the rifle receiver's crown.

Abstract: An adjustable rear pistol sight has a sight base and a sight block. The sight block is secured in a recess in the sight base and has both windage and elevation adjustment capabilities. The sight base has a dovetail that will be receivable in a cooperatively shaped notch in a slide of a pistol with which the adjustable rear sight is intended for use. The sight has no sharp edges or surfaces and is essentially snag-free.