With these aluminium hexagonal standoffs, you can mount expansion boards or HATs with standard-size female headers on your Raspberry Pi. The body of each male-female standoff is 11 mm long by 4 mm wide. A male thread extends 6 mm past the standoff body, while a female thread extends at least 6.35 mm into the body. Standoffs can be made longer by screwing multiple units together. M2.5 threads are used on both ends, since these are the same size as Raspberry Pi mounting holes.