8108: Rat Hat BottomPinnacles wireless rat systems employ our signature Rat Hat, which houses the electronics, battery, guide cannula and biosensor. The bottom is affixed to the skull via anchor screws and dental acrylic. It has an opening for access to the skull. Bottoms are not reusable. The Rat Hat bottom comes in multiple varieties: 2. 4GHz Wireless: 2 Channel Biosensor 3C: 3 Channel Biosensor S1: Fixed Frequency Biosensor; Frequency Agile Biosensor WSL: EEG EMG;