Napoli Cup has brought back the green hard courts. These courts were popular in the 1990s but they were discontinued because it was hard to see the ball because of the lack of contrast between the color of the ball and the color of the court.
Tournaments then moved to blue courts which made it easier to see. Grand slams such as the US Open and the Australian Open also moved to the blue courts. Over the years, blue hard courts became ubiquitous.
The tournament in Napoli is typically a Challenger event but was upgraded to ATP 250 level event this year because of the cancellation of tournaments in China due to COVID-19.