The type of undermount sink bars that sit horizontally are typically **sink support brackets** or **mounting bars**. Common types include:
1. **Metal support bars**: These run horizontally across the cabinet and provide strong support for the sink.
2. **Sink clips**: Used in combination with adhesive to secure the sink to the countertop.
3. **Rail systems**: Adjustable bars that can be mounted beneath the countertop to hold the sink in place securely.
Each system ensures the undermount sink is properly supported without visible fixtures.