Can you wait and buy it when you arrive? NO
these are small metal hooks shaped like question marks, with a screw thread along the shaft. They are easily twisted into anything wooden, from trees to roof beams.
When you need to hang a mosquito net but there are no attachments on the ceiling or wall, a couple of small screw in hooks do the job and create almost no damage.
They are also great as anchor points for washing lines, clothing lines indoors and for hanging mugs etc off a wooden support. If you lose them, they seem to be very hard to find in Uganda, although you will easily find nails and normal screws.