It's a First Generation model (Lockdown filler). I've got one in this color and it's one of my favorite pens -- it's been in constant rotation for roughly 3-1/2 years at this point (I can't even say that about my Plum 51). I know the the Shadow Waves are lower tier model Vacs (lower grade celluloid, and didn't have the same level of warranties) -- but I think they're often prettier than the Pearl models. I was lucky in that mine had already been restored when I got it, and I haven't had to replace the diaphragm or do any maintenance (other than refilling it when needed) except for very recently -- the tassie (metal circle) and jewel the screw on bottom) came off the blind cap (the part hiding the button-looking part at the end of the barrel in your second photo) -- but fortunately I found them, and I just need a little thread sealant (which I might have) brushed on the threads of the jewel). Not bad for a pen that is roughly 80 years old....
Depending on the girth, yours could be a Junior or a Slender Junior, according to the Vacumatic Guide on Tony Fischier's website, which has a photo of the relative sizes between Junior, Slender Junior and Sub-Junior (the Sub-Junior is quite a bit shorter but sounds as if they were phased out around 1934): http://parkercollect...cinfoshell.html (the main article about Vacumatics is here: http://parkercollector.com/vacumatic.html).
Mine has a 4th quarter 1937 date code: 47 (the system of dots for the quarter come later). The date code will be at the end of the barrel imprint, right after it says "Made in USA" (assuming it hasn't worn off over the years).
Hope this helps.
Ruth Morrisson aka inkstainedruth
"It's very nice, but frankly, when I signed that list for a P-51, what I had in mind was a fountain pen."