Does anyone have any recommendations on what air hose to use for air assist?

Does anyone have any recommendations on what air hose to use for air assist? Right now I’m using a polyethylene air hose (from http://www.harborfreight.com/20-pc-air-compressor-starter-kit-61310.html) but it seems too rigid, should I go get a rubber hose instead?

I use 5x8 flexible tubing. It is soft and flexible, but holds well enough to be routed for air assist.

http://www.lightobject.com/5X8-Silicon-Flex-Tube-for-Air-Assistance-or-Water-Cooling-P776.aspx

What works well is to put a fitting (preferably with an adjustable valve attached) on the back or side of the unit and on the inside have it connected with a barb to silicone or small vinyl tubing which is much more flexible when attached to your laser head.

I’ve posted this elsewhere, but here’s a link to a photo of the air connector and valve I used. My total cost was about $10 and it used silicone tubing to the head on the inside.