Description

The Sierra 18-9800 Compression Tester is interchangeable with the following: Mallory 9-79804. Each Sierra product meets or exceeds the original equipment part it replaces. Designed specifically for hard to reach bottom spark plug holes on older Mercury models.
Sierra Compression Tester
Meets or exceeds the original equipment quality
Perfect for hard to reach bottom spark plug holes on older Mercury models
Interchangeable with the following: Mallory 9-79804