The size of synthetic clay mitts is typically standardized across different brands and types for several reasons:

1. Ease of Use: A standard size ensures that the mitt fits comfortably in the hand, making it easier to manipulate and use during the detailing process.

2. Consistency: Standard sizing allows manufacturers to maintain consistency in production, ensuring that each mitt performs uniformly and meets quality standards.

3. Efficiency: A consistent size makes it easier for users to switch between different mitts or replace worn-out ones without needing to adjust to different sizes.

4. Packaging and Storage: Uniform sizing simplifies packaging and storage logistics for both manufacturers and consumers, as mitts can be stacked or stored efficiently.

While synthetic clay mitts are generally similar in size, they may vary slightly depending on the brand or specific model. It's essential to choose a mitt that feels comfortable and provides effective cleaning for your car's surface.