Yeah. Not complicated. The holes are 5/16" in diameter and about 4" deep. I hung it on the chain link fence on the western edge of the garden, facing East. This is supposedly the correct orientation because the sunrise will wake up the little critters and encourage them to go out and forage.
The idea behind attracting mason bees is that they are effective pollinators. This is great, but based on everything I've read, I'm unconvinced that they will help at all with my garden. The mason bee lifecycle dictates that in the spring, they will look for a suitable home like this one, and start laying eggs in layers inside those holes. Come summer, the adults die and the young begin to develop. The following spring the new adult bees fly out of the nest and the cycle continues. This is different from honeybees, which are social insects, and forage throughout the year. Here in Eastern Ohio, I don't have a whole lot that's waiting to be pollinated in the early spring. How effective these bees are to my garden will depend on how early my plants have blossoms, and how long the bees actually take to complete their nest building. Whatever - we'll see. That's why they call it an experiment, right? At the very least, I'll be bringing some happy buzzing to the garden. That's the best part - these bees rarely sting!