Important kit you might have forgotten?

[Wolfiesmith]

We all have our different bits and bobs that we wouldn't be without, many of them are common to all of us, a decent knife etc. However, there are bits of kit that aren't necessarily mentioned that often, but can be considered vital to some. To that end I thought I'd create a thread in homage to these bits of kit. Feel free to add your own "important, you just might need it" bits and bobs if you feel you have something worth mentioning.
I'll start with my own personal favourite, which are a decent set of Bino's. They are great for recce's and general distance surveillance and could mean the difference between life and death. Seeing a threat from distance could give you enough time to avoid it or prepare a decent defence. They could also give you time to decide whether someone is a friend or foe while you are undetected. Other uses include spotting prey when hunting etc.
The good news is that you can find frequently find a decent set at bootsales and the like, so they needn't be expensive. I picked up a great pair just like this, for the princely sum of £12.
Well that's my suggestion, what's yours?