This ships free when ordered with a March Scope. Shipping fee added if ordered alone. 
36mm Inner Diameter Middle Focus wheel. 2-DB342-0

For illuminated models of: 

Middle Focus Wheel

• To help with fine or rapid focus changes at different distances, March scopes can be upgraded using a 49mm diameter Middle Focus Wheel. It will assist making quick and fine adjustments easier with the focus knob.

  2-DB340-0

  for Fixed power 48×52, 40-60×52 EP Zoom,
  non-illuminated models of 10x-60×52 (D60V52L & D60V52LM & D60V52T & D60V52TM)
  (inner diameter 31mm)

  2-DB341-0

  for non-illuminated models of
  1x-4.5x, 1x-10x, 2.5x-25x, 5x-50x, 8x-80x, 1x-8x, 3x-24x, 5x-40x, 10x-60×56, 4.5-28×52, 6-60×56
  (inner diameter 34mm)

  2-DB342-0

  for illuminated models of
  1x-4.5x, 1x-10x, 2.5x-25x, 5x-50x, 8x-80x, 1x-8x, 3x-24x, 5x-40x, 10-60×52, 10x-60×56, 4.5-28×52, 4-40×52, 6-60×56
  (inner diameter 36mm)

  2-DB729-0

  for 5-42×56 illuminated models (inner diameter 39mm)

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