I have 180 cm Fischer Big Stix 10.6. w/135 mm tip. Would it be better to get the medium or long skin? Either would likely work, but which would be the better fit?

Tech Specs:

Material:

synthetic 

Tail Attachment:

tail clip and strap 

Bag Included:

yes 

Weight:

(x-short) 14.5-23.2 oz, (short) 15.2-24.5 oz, (medium) 15.9-25.8 oz, (long) 16.6-27.1 oz, (x-long) 17.3-28.5 oz 

Recommended Use:

alpine touring, ski mountaineering 

Manufacturer Warranty:

60 days