Superior Labs 2 1/4" Diamond Mechanical Tachometer SL1010-12330-13-H05. Superior Labs (SLI) is the aircraft tachometer of choice by many OEM’s due to its precision and reliability. The Superior Labs 2 1/4" Diamond Mechanical Tachometer SL1010-12330-13-H05 has a Green ARC of 700-2800, and a Red Line of 2800. 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 Diamond DA20, and G500 Models; Mitchell D1-112-5223.