Booking time range

in the Booking time range / Define the time range in wich customers may book an appointment

I would like to change the time to 12 Hours

Today the choices are: 15min, 30min. 1H, 2H, 3H, 4H, 8H, 16H, 1 day etc.etc.

Where can I add new time:

 <div class="sln-box sln-box--main">
        <h2 class="sln-box-title">Online bookings tid </h2>
<div class="sln-box--sub row">
    <div class="col-xs-12"><h2 class="sln-box-title">Booking time range <span>Define the time range in wich customers may book an appointment</span></h2></div>
    <div class="col-xs-12 col-sm-6 col-md-4 form-group sln-select  sln-select--info-label">
        <label for="salon_settings_hours_before_from">Varigheden starter</label>
        <div class="row">
            <div class="col-xs-7">
                                        <select name="salon_settings[hours_before_from]"  id="salon_settings_hours_before_from"   class="" autocomplete="off" >
                                        <option value="+15 minutes" >kvarter</option>
                            <option value="+30 minutes" >halv time</option>
                            <option value="+1 hour" >1 time</option>
                            <option value="+2 hours" >2 timer</option>
                            <option value="+3 hours" >3 timer</option>
                            <option value="+4 hours" >4 timer</option>
                            <option value="+8 hours" >8 timer</option>
                            <option value="+16 hours" selected="selected">16 timer</option>
                            <option value="+1 day" >1 dag</option>
                            <option value="+2 days" >2 dage</option>
                            <option value="+3 days" >3 dage</option>
                            <option value="+4 days" >4 dage</option>
                            <option value="+1 week" >1 uge</option>
                            <option value="+2 weeks" >2 uger</option>
                            <option value="+3 weeks" >3 uger</option>
                            <option value="+1 month" >1 m?ned</option>
                            <option value="+2 months" >2 M?neder</option>
                            <option value="+3 months" >3 M?neder</option>
                            <option value="+6 months" >6 M?neder</option>
                            <option value="+1 year" >1 ?r</option>
                            <option value="+2 years" >2 ?r</option>
                    </select>
                </div>

The page I need help with: [log in to see the link]