When I first started constructing themeless puzzles in 2016, I dared not stray far from the same basic grid pattern of triple-stacks in each corner (see, for example, The New York Times1/27/17, 5/19/18, and this Friday, 9/14/18). Which meant that my notebook was full of 11-letter seed answers. In 2017, I got my legs under me enough to venture into more challenging and interlocking designs. But I still had a whole bunch of 11-letter seeds to try out. Thus, RAREFIED AIR and SERIAL DATER were the seeds for this puzzle. Enjoy!