In addition to the round outlets, Unico also manufactures rectangular outlets. The rectangular outlets feature a narrow width slot that gives a better appearance in a sidewall installation. There are four (4) different types of slotted outlets. The type of outlet not covered by this bulletin is connected directly to the plenum and is described in Bulletin 20-58. This bulletin covers the three outlet types which are used in conjunction with the Sound Attenuator supply tubing. The Unico System patented 90 deg slotted outlets (UPC-66 and UPC-67A) are specially designed to quietly turn the air inside a typical wood frame stud wall cavity. The 90 deg outlets are particularly useful where there is insufficient room to provide the minimum sound attenuator bend radius. Other applications for the 90 deg outlet include placement near the perimeter of a low-pitched roof, and in applications with only a small cavity between a dropped ceiling and the roof.