This is a long sleeved knit top from Chico's Zenergy. Mock turtleneck, cold shoulder, long sleeves. There is a gold zipper running the full length of the back. I didn't get the zipper to separate at the bottom, but I didn't try very hard. I'm not sure if it's supposed to separate or stay attached.

This is a true black color, with wide cable knit stripes.

Soft light weight rayon blend. Size 0, or Small, 6.  Please see photos.

This came from an estate sale where the woman had tons of clothes, so most items show no wear. No issues noted. I will have lots of Chico's clothes listed from this one estate, as well as similar brands like White House Black Market and others. I'm always happy to combine shipping. 
Chico's sizing is:

CHICO'S SIZESUS SIZESCHESTWAISTHIPARM
00XS/232½"-33½"27"-28"35½"-36½"22⅝"
0S/433½"-34½"28"-29"36½"-37½"22.75"
0.5S/634½"-35½"29"-30"38½"-39½"22⅞"
1M/836½"-37½"31"-32"39½"-40½"23"