They are available to be purchased in a number of options depending on your budget and preference as follows.
Build outdoor pull up bar.
For example build a pair of parallel bars for dipping exercises.
With help from some of the pictures on your site i was able to build a pull up bar and dip station.
For the poles i used 1 galvanized pipe 5 wide.
Expand your pull up bar as needed for other exercises.
Outdoor pull up bars have become increasingly popular with the recent explosion in popularity of crossfit.
Having more room to do certain movements like muscle ups or just being able to soak in the sun and hear the birds singing as you do your pull ups.
Bar only you purchase a straight pull bar with bolt holes and bolts.