Break Away 2.54mm, 0.1" 40P Breadboard PCB Protoboard Connector Stacking Header Female Extra Tall Header for Raspberry Pi for Arduino (Pack of 5)

There are two cheaper headers you can get. The ones with the long pins, and the ones with the short pins. The short ones aren't even worth talking about - I keep running into problems with them because the pins they use are "flat" instead of "square", and they don't make reliable contact with the header below. I wasted an hour last week trying to figure out why an arduino shield I made wasn't working. Turns out a pin, fully plugged in, wasn't making contact! Had to give it a 90 degree corkscrew twist to work. These are much more reliable with heavy, square pins. They also have a little added "neck" on them that makes them easier to cut, but beware, it also makes them slightly taller when stacking shields, especially if you need to connect to the SPI header in the middle. The cheap headers with the short (flat) pins are of very limited use because they can't stack. So these are the winner when it comes to stacking headers.

These are solid and can be cut with dikes, but it will damage the adjacent pin/socket.

Cumplio

This is not a breakaway header.The solid plastic comb is not breakaway at all. The strip in which the socket pins are inserted is, but the pins are not going to be easy to remove without cutting. Shortening this connector requires removing one pin.One method of shortening the connector would be as follows (not tested):1) with fine flush cutters, cut the breakaway base to the desired length and isolate the pin by cutting on both sides.2) the pin should be able to be pulled out.3) using the flush cutters, cut through the middle of the comb lengthwise.4) trim the edges of the comb.Since the comb is not a breakaway, the entire connector assembly is not break apart.This is used as an extension to monitor displays with a custom PC board. Plug in the PC board, attach monitor leads, and plug in the display.