Superior Labs 3 1/8" Beechcraft Mechanical Tachometer SL1010-64025-09-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" Beechcraft Mechanical Tachometer SL1010-64025-09-N00 has a Green ARC of 1750-2600, a Red Line of 2600 and records at 2310. SLI also offers precision aircraft tachometers for aftermarket replacement for most single engine aircrafts. 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 Beechcraft H35 Models.