You have some choices when it comes to handlebars on your pro scooter. First you need to decide what material you prefer; steel, chromoly or aluminum bars. The steel and chromoly are the strongest bars and are great for taking the brunt of hard punishing stunts. The aluminum bars are strong enough to take a beating but are much lighter then steel or chromoly handlebars.
The one piece scooter are bars are the choice of any serious rider and provide the stability and feel to give you confidence when attempting tricks and stunts.
Scooter bar height is really a personal preference. Don't be afraid to cut the bars if you are a shorter rider... Just measure twice and cut once!