Superior Labs 3 1/8" Piper Mechanical Tachometer SL1010-64001-10-N00. Superior Labs (SLI) is the aircraft tachometer of choice by many OEM’s due to its precision and reliability. The Superior Labs 3 1/8" Piper Mechanical Tachometer SL1010-64001-10-N00 has a multiple width Green ARC of 500-2000;2200-2575, a Yellow ARC of 2000-2200, a Red Line of 2575 and records at 2292. SLI also offers precision aircraft tachometers for aftermarket replacement for most single engine aircraft. SLI manufactures aircraft tachometers for all general aviation aircraft types and offers custom screen printed dials, internal lighting, anti-glare glass, and pre-set engine hours. This specific unit replaces a Piper P/N 599-198.