These guide cannulae fit BASi™s most popular œBR style brain microdialysis probes. There are two version of this guide; they differ in how they secure the probe or stylete in the guide. One uses a rubber O-ring that lightly snaps into the notch in the probe or stylete head when inserted. Removal is equally simple. The other uses an Î© (Omega) ring that can be turned to open the ring™s œwindow to allow insertion of a probe or stylete. When the omega ring is turned further, closing the window, the probe/stylete is locked securely in place. Removal is equally simple. If you are working with mice, see the MBR style guides.