Cat Ear BarsFeatures 505232 and 505333 Non puncture Cat Ear Bars have a 45 taper, and do not puncture the tympanic membrane. Compatible with all WPI Rat Stereotaxic Instruments 505231 and 505332 Traditional (20) Cat Ear Bars taper at the tip to penetrate far into the ear canal for a more secure hold. Options Order code Description 505231 Cat Ear Bars, 20 degree 505232 Cat Ear Bars, Non Rupture 505332 Cat Ear Bars, 20 degree for Rail Stereotaxic 505333 Cat Ear