What do you keep in your 'first aid kit'??

Certain items like medicines are iffy to keep around on a "just in case" basis due to how short the shelf life can be. But, I like to keep a couple spare powerheads, my old light fixture, a couple spare light bulbs, a fish trap, and a QT tank around on top of the regular supply of equipment and test kits in case there's an emergency.
 
I have a couple of hospital tanks (filter kept in the sump), test kits, net, trap, pipe cleaners (algae is hard to get rid of down the narrow pipes!!!), towels, tissues (I always make a mess, epoxy, scalpel, superglue, spare powerhead, heater, thermometer, rowaphos, polyfilter, a water butt always full of RO water and for the real big emergencies - my credit card!!!:)
 
in a box in the fish tank stand
 
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