24 hr transit visa or 5 days visa ?

She will use 5 days Shenzhen visa on arrival. She will obtain a Shenzhen visa on one of three designated border crossings that have visa offices, but she has to take care that she arrives at the border crossing before the opening time of local visa office. If she decides to go through Lo Wu (Luohu) crossing, she is advised to be there at least at 08:30 to avoid later longer queues. The price of Shenzhen visa is 130 CNY and it should be paid by card. Most of the cards are accepted.

After her stay in Shenzhen, she can return back to Hong Kong by taking any border crossing and any mean of transport, high speed train included.