Your name is Crape Myrtle, Lagerstroemia.

...and 'hardy' is an temporary thing for Crepe Myrtle in zone 6A. Temperatures much below 0 to -5F will kill it to the ground. Might be why it's only 10' tall.

there's so many here. I would like to buy a bunch but...I know about the crapes. Wonder why there's so many here. Short but healthy. Beautiful

Maybe that certain area has a local zone 7 climate

The hardier varieties are hardy to 6b (NJ ranges from 6A to 7b), not including microclimates. That being the case, they will be most common from northeastern NJ down the shore (and further west, as you you go south). Ultimate height can vary depending on..., the particular cultivar, the particular zone, and pruning habits (many are cut back seasonally to be maintained as shrubs). Are you in NJ? Approximately where? In areas where they are common, they tend to be mist available from May into summer. I would not plant them until the Fall though.