Designed for easy insertion into the cap of the heart chamber, these cannulae have a female Luer connection formed on a 4mm O.D. glass tube. The cannulae taper down to outside diameters of 1.4mm to 3.0mm. The ends are slightly flared and etched to provide a no slip connection to the aorta without damaging the vessel wall. The design permits the cannula to be rotated or adjusted easily during mounting of the organ and then secured by tightening the enclosure surrounding the cannula. These cannula are suitable for most rat, rabbit, and guinea pig cardiac preparations. 120153-ST is the standard size. 120153-LT is a long, gradual taper which is also available. In addition, Radnoti Glass Technology will provide custom sizes or single size sets upon request. Constructed of borosilicate glass. ** For pressurized systems, such as the heart, a long narrow cannula will offer more resistance than a short cannula pulled down from a larger tube. Other considerations are the ease of mounting and tying the organ or vessel, which is reflected in whether the experimenter prefers a lip or ridge on the cannula as opposed to an etched surface. A longer cannula may be easier to position than a shorter cannula. Normally small diameter cannulae are more fragile and must be considered expendable. In many cases stainless steel or plastics such as polyethylene or teflon can be used to reduce cannula breakage in these situations.