SME is known as a premium maker of tone arms and analog accessories for turntables. Formed in 1946 as the Scale Model Equipment Company Limited, SME began as a manufacturer of scale models and parts. In the 50's, the company started manufacturing the more specialized parts, eventualy the tonearms and turntables they're now known for.

Notable SME products include:

SME M2 Tonearm
SME Model 10 turntable
SME Model 309 Tonearm

HomeTheaterReview.com's SME product reviews include:

SME M2 Tonearm
SME Series I, II, III Tonearms
SME 20/12 and 312S Tonearm
SME Series 30 Turntable

There is also a history of the brand on Wikipedia.

Similar to SME are companies such as Clearaudio, Simon Yorke, and Linn.