The Sigg Oval 0.6 Litre bottle that comes with the Canteen is stainless steel so is unlined. The outer is powdered coated so the neoprene cover is recommended as well.

http://www.amazon.co.uk/Sigg-Bottle-Insulation-Bottles-Neoprene/dp/B000OT23VQ/ref=pd_sim_sg_2

I believe that Sigg also do an identical Oval bottle in Aluminium so would be lined.

http://www.amazon.co.uk/gp/product/B001NPEMSM/ref=twister_dp_update?ie=UTF8&childASIN=B001NPCWG6

The combo Bottle+Mug item should always be stainless steel construction, but I would also check out the Tatonka Bottles as well. They are very lightweight for Stainless steel and fit perfectly into a Sigg Neoprene cover.

http://www.amazon.co.uk/Tatonka-Stainles...3163&sr=1-1

I also use a Smartube with the Tatonka Bottle in day pack side pockets as shown below

http://www.amfearliathmor.pwp.blueyonder.co.uk/CIMG0062eh.jpg

Many thanks, some times I find that I come across something on the net and no matter how many searches I do I can't find answer's to the simple questions (the one that make you fell silly for asking). As for those other bottles I've found that the cylindrical shaped ones are a PITA to use in my small rucksack (I pack light and they don't stay where i want them)

PS: Sorry to keep bugging you like this but could you tell me the weight of the flask with and with out the cup please. Again, many thanks