I use some...
plain label SAM splints in my work kit. Get em from BP Medical out of NYC.
They roll up small, can be cut easily into just about shape you'll ever need, won't deflate like an air splint and they're much cheaper.
I'd buy some original SAM's but frankly, they're just too damned expensive for what they are, thin sheet of aluminum covered with some foam in an item that's going to be thrown away after use.
You Reading This: Stop
Don't just stay tangled up in your life.
Out there in some river or cave where you
could have been, some absolute, lonely
dawn may arrive and begin the story
that means what everything is about...
William Stafford 1914-1993