The Grover GRO107C Self-Locking Rotomatic Machine Heads offer the same Rotomatic quality as the GRO102 model mentioned previously, but with some key differences:

1. 18:1 Gear Ratio: The GRO107C features a higher gear ratio of 18:1. This means that you'll experience finer and more precise tuning adjustments with these machine heads. The increased gear ratio provides greater control over the pitch of each string when tuning.

2. Self-Locking Internal Cam: These machine heads are equipped with a self-locking internal cam string post. This innovative design allows for easy string changes and quick string tensioning. Simply insert the string through the string hole, pull to tension, and begin tuning. The self-locking mechanism securely holds the string in place, eliminating the need for winding multiple turns around the string post.

3. Rotomatic Design: The GRO107C retains the classic Rotomatic design known for its stability and ease of use. The Rotomatic machine heads have a solid reputation in the industry for maintaining tuning accuracy and stability during extended play.

4. Diecast Housing: These machine heads are built with a deluxe diecast housing that provides durability and reliability. The diecast construction ensures that the tuners can handle the demands of live performances and regular use.

5. 3-a-Side Configuration: The GRO107C is designed for guitars with a 3-a-side headstock configuration, making it suitable for various electric and acoustic guitars.

Overall, the Grover GRO107C Self-Locking Rotomatic Machine Heads offer superior tuning precision with an 18:1 gear ratio and the convenience of a self-locking internal cam string post. These features make them a great choice for players who require quick and accurate string changes, as well as fine-tuned adjustments when tuning their instruments. The Rotomatic design and diecast housing further enhance the overall durability and performance of these machine heads.