Booking holiday for specific times

We want to let people specify what time they want to book holidays for. Lets say someone works 07:00 - 15:30 and they want to take 2 hours holiday from 09:00 - 11:00 because they need to do something. At the moment there's no way to specify that other than adding a comment, otherwise the only options are AM and PM.

It would be good to be able to specify the times, just like with Other Events.