What is the difference between a closed wrap trigger trombone and an open trombone?

Open wrap trombones have the slide tubes directly exposed. Closed wrap trombones bend the tubing back around on itself to shorten the overall length of the instrument, which can make it more comfortable to play for some people.

Closed wrap trombones are said to be more precise and accurate in intonation than open wrap trombones, as the tubing does not need to bend as much to reach certain positions, therefore, resulting in the instrument being more precise in tune in comparison.

Both types of trombones have their own advantages and disadvantages, and the best choice for a particular player will depend on their individual needs and preferences.