fenix PD30- I have several, bought for exactly the purpose you describe.
Small diameter, fits in pocket..about 5" long.
non aggressive texture.
runs on 2- 123's, and frankly, after seeing the exceptional run time, I would not use anything else.
has a low, medium,high , twist the bezel and you get strobe and ultra high setting, (pre selectable). about 275 lumins on high.
I carry this every day . all day, all year. It is used once , twice, 10 times in a day, mostly to look into a machine or electrical box, sometimes to check out the yard for creatures, it is an amazingly useful and flexible tool.
When I am in the city I set it for strobe, just as a tool to disorient aggressive folks.
I change the batteries once a year or so, when they get low, the only the low setting works, with a very slight strobe to let you know.
durability is great, never had a problem-the anodizing is wearing off from bouncing around next to my keys, but overall, this is the best light I have ever used.