Who has the best detail mapping for the Texas gulf that is compatible with HB Onix?

Check out the Platinum + card from NAvionics....
http://www.navionics.com/en/platinum-plus


It has a ton of info, with all Gold features plus: 3D and Satellite Overlay, Panoramic Port Pictures, dynamic Tides & Currents and much more!
https://www.youtube.com/watch?v=YRx5gZIFLJk&feature=youtu.be

You can also check out the WEBAPP for all of the mapping for your area....for FREE!!

http://webapp.navionics.com/?lang=en#@7&key=%7BnlpDfne_Q

Does it have inshore and offshore?

Allan, check out the Nav+ card if you are wanting to get multiple areas. The way that is works is, you purchase the card and it is preloaded with all of the US with premium data, once you plug it into your computer to update, it will ask if you want to purge that data. In your case you would purge the data and draw boxes around the areas you would like to fish. Check out the free webapp so you can viw your areas before making a purchase:

http://webapp.navionics.com/?lang=en#@3&key=_kwwG_wfhA

Hilton's realtime navigator.
everything above, plus near-realtime bathymetry, chlorophyl, & temp charting

https://realtime-navigator.com/signup/

Is this a chip and what units is it comp/w.