Does anyone know more about these bikes ?
Firestone Cruiser ,New Departure <(model?)
New Departure is stamped on what looks likes could be an anti axle wrap device to prevent wheel hop. Its affixed to the frame at axle /hub mounting point ....otherwise I'd have no idea what it could be )

It also has dual or twin chrome coil springs in front of the post/handlebars area.
Before I got it in 1972,It had been used by father as an exercise bike (had a rear tire/frame lift stand looked good enough to have been an option for the Firestone or a good after market or diy)
Specs I could easily locate:
1- frame is 17 or 18" (center lower frame to top of top frame. Im not sure how to measure height when the top bar curves downward about an inch. So I figured both ways and come up with 17/18" Ht
2- Wheels: 22 5/8 dia x 1.25 to 1.75 in rim width. Used tape,but will locate/use calipers to narrow that range unless someone already knows the correct msmt.
3- Axle wrap device?
4-New Departure:
5- exercise stand for the bike. Was it an Option or a well made after market or DIY part?

New Departure was a brand of coaster brake hub. The "axle wrap thing" is the coaster brake reaction arm. See Sheldon Brown for more information: New Departure Coaster Brakes for Bicycles

Serial number is most likely on the drive side rear drop out, or on the bottom of the crank housing.
Be aware that the serial number may be hard to see or read, depending on how thick the factory put on the paint, and how deep they stamped the numbers.

You can see thecabe.com for more information about classic and antique bicycles, tricycles and other topics as well...