2 x 20 Pin Stacking Header Female Pin Header Compatible with Raspberry Pi (Pack of 4)

Works as expected but the pins are a bit long. One minute with a pair of side cutters takes care of that.

Only complaint is the pins are thin/fragile. I was expecting these to be stiff/same diameter as a header pin, but they are not.

The pins are very thin and too long. Hard to use them with typical wires as the pins bend waaaay too easy under light push. And they tend to stay loose because of their thinness and disconnect on almost every touch to the wire. I will most likely return. Not worth even a penny. I wish there was a rating of 0 (zero!) Update: to their credit, the seller offered a refund which I accepted.

The description says "Size: With a standard pitch of 2.54mm, it is very suitable for Arduino or other electronic circuit boards." The problem is the pins are not square but flat and do not make a strong electrical connection. I tried two PoE Hats, which worked with a Raspberry Pi 3B+. Neither PoE hat works with the stacking header. If I remove the stacking header everything works fine. I assume the problem is because of a poor electrical connection caused by the thinness of the pin, but the stacking headers may not work at all. I purchased square header pins and these work fine

I needed to fill a gap to cover a cooler. I tried stacking 3 of these and the pins pushed right out.

Pins are too long for stacking.

The pins are too thin, and bend too easily. These are very difficult to install because the pins don't maintain their shape, and bend when unstacking.

Pins are not even square. And doesn't make proper contact with Pi header. Don't waste your money on these.