Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
On the A380 wing are at least 3 red circle each side. There seems to be a black part inside. Is this a dip stick, or something else?
They are likely attach points for safety harness equipment. Workers working on top of the wing attach gear that functions as anchors for lines that run the length of the wing, then attach their safety harness to the line.
Required, but never shown