This 'shorty' 2x20 header is great for a slim connection to your Raspberry Pi model A+ or B+, it's basically the  through-hole version of the SMT GPIO Header for Raspberry Pi HAT - 2x20 Short Female Header.

This header is for super-slim through-hole designs.  It's a custom-made, 2x20 short female header that can be used to plug a Raspberry Pi HAT onto a B+, A+, or Pi 2. It's easier to use than the SMT type headers, but it's great for the slickest, slimmest fit, that a through-hole Raspberry Pi header has to offer.