What is the purpose of the removable shield that sits underneath the hatch window, I have had the car for 3 months and never noticed it before. I had a large box in the cargo area. I shut the hatch by hand and knocked it half way off.

 

IMHO, it's there to be knocked-off as you (AND I) have done, and then potentially rattle -- but also as an extension to the tonneau cover when it's extended. As discussed in some old 2012 threads, with the 2013 refresh, Lexus eliminated the flaps that used to connect from the back of the rear seats to the roller section of the tonneau cover. When the flaps were there, as well as "the shield" you reference, contents in the entire cargo area could be fairly well hidden when the tonneau cover was extended. Now, there is the gap at the back seat and IMHO having a little space near the rear hatch where one could look into the otherwise enclosed cargo area wouldn't be a big deal.

 

Thanks! I kind of thought that was it.

 

I have a 2010 and I didn't realize they removed those flaps that connected to the back seat in later models. They are a bit fiddly but I find them handy to hold a roll of paper towels, some microfiber cloths, and a spray bottle of window cleaner without them moving around. The large shield referenced is unobtrusive until you load something big in the cargo area and it gets knocked off when the hatch closes. It is a security feature for prying eyes but with the window darkly tinted from the factory I'm not sure how effective it really is.

 

Marqevans - I too knocked the removable shield off, and found it tricky to reinstall. Lots of wiggling and shoe-horning got it in, as I recall.
Ray A.