widely available for purchase, they are very short ls3 height with the nippon denso connector
for a big overview of injector physical size and connectors check out the Fuel Injector info / Physical size / connector types page
you can buy these all over the internet for varying prices but i recommend buying them from my buddy VSracing.net so you can make sure you dont get knock offs
CBM motorsports sells nice hats to adapt these to taller rail setups, or to drop them in to stock truck rails.
here is the "small hat" setup that is just under 1 inch
third picture you can see it will take a 210, or ls3 height to ls2 or truck height, and it will take a truck height or ls2 height injector to LS1 or the tallest height
Here is the taller Hat they sell for ls3 strait to ls1 height