Penguin Ambidextrous Vertical Mouse by Posturite is designed to help eliminate forearm pronation. It has fine cursor control and Bowtie switch that allows users to switch between right and left.

Features

• Available in three sizes small, medium, and large
• Adjustable DPI: select from four pointer speed settings 400, 600, 800, and 1200 DPI
• Rubberized oversized scroll wheel
• Bowtie Switch allows user to switch from right to left hand use.
• Has  fine cursor stability and pointer accuracy
• Eliminates forearm pronation 
• Also available in wireless option

Specifications

• Base:
• Small 4.88'' W x 3.88'' D
• Medium 4.25'' W x 5.38'' D
• Large 4.75'' W x 6.0'' D
• Height:
• Small 3.0''
• Medium 3.5''
• Large 3.88''
• Weight:
• Small 146 grams (0.146 kg)
• Medium 187 grams (0.187 kg)
• Large 223 grams (0.223 kg)
• System Compatibility : PC - Windows XP, Vista, and 7 and Mac - OS X
• Finish Black and Silver
• Interface 2.0 USB
• Manufacturer warranty 2 years

Sizing Guide: Measure in cm from the base of the wrist to the top of the middle finger. Size small 0-16 cm ( 0-6'' approx) , medium 16-18 cm (6-7'' approx), large 18+ cm (7'' + approx).