Kookagee, I would recommend you do a google search for reviews comparing the Buffalo Mountain Shirt vs Buffalo Special 6, vs Montane Extreme Smock, etc. A few blogs, forums or videos can be found that are more than just supplier websites giving you a sales pitch.
The Special 6 seems to be the same thing only made with a little tougher materials, and some people like the Montane product better, seems that Buffalo invented the basic idea, and Montane wanting in on the action, added what some people feel are improvements. afaik, both are made in Sheffield. And there are similar products from both companies that are lighter weight models. Or similar competing products are made by Rab, and other companies. I have found the Buffalo shirt to be too warm to wear unless it is pretty chilly out. And their design purpose is to eliminate layering, substituting opening the zippers to vent in cooler air when you’re to warm, or zip up when it’s cooler or you’re less active. Last evening I found there is a buffalosystemsusa website, but their offerings are few, and about $60 higher in price. Shipping from Dublin or Cork is only about $10 ~ 13.
I don’t know if the Jackson-sports webpage now automatically switches to USA pricing. It does for me, but that may be due to cookies. If it doesn’t automatically switch over this is the process I had to use this process: First, Go to the bottom of the page and click on Shipping, select shipping to USA. This removes VAT from the price. Next - Go to the top and switch the currency to US Dollars. This will both remove the VAT from the pricing, and give you pricing in USD, and estimated shipping in USD.