Connect to those pesky 0.5mm pitch connectors that you may run across with an FPC stick. Adafruit designed this for use in house, to quickly connect to 50pin 0.5mm pitch flex cables they need to test. But they also thought it might be useful for our customers. There’s a 50-pin long connector on top, and they have one very long ‘mechanical’ pad. Since the pad extends along the entire length you can use any size 0.5mm pitch connector you wish (Adafruit seems to bump into 40 and 50 pin the most). Each pad is broken out to a 25-pin long 0.1″x0.1″ spaced header. One side is doubled on the opposite side to make it bread-board friendly. It can accommodate most ZIF and snap connectors and will make prototyping much easier on you!
Each order comes with a single PCB stick, no header or other connectors included.