What is it?
Just like the picture you can use this waterproof kit to do some interesting things. There are 5 holes could be drilled on the button,and the space inside is big enough to put battery and control board.
For the details of 2dB antenna please see https://www.tindie.com/products/lspoplove/dstike-waterproof-mushroom-2db-antenna/
I plan to design a control board for this kit in future