Hi Jim - Yes, absolutely legal in the US. At its heart, it's a flashlight with some added capability. Thanks for the nice comment about the sales page. I'm really sorry I can't ship this to the UK.
Here's a little insight on that - my added shipping cost for the US is $3.95. That is just to increase my unit profit. My supplier has a US warehouse and charges me $0.00 for shipping. So, for US customers, I'll get an extra 4 bucks in profit. For the customer, the whole purchase price is below $20.00 which is very favorable. Many people are offering these for up to $69.00 (and more).
Thanks for taking a look and commenting. Best - MM