This is an original TNC-X from Coastal Chipworks. It is for use on a Raspberry Pi. I built the tnc from a kit but never hooked it up. MFJ now makes a version.
Documentation, schematics, etc. at
Price $50 obo plus shipping, PayPal F&F or USPS money order. My email good on QRZ.com
Mitch W4OA