If you want a skin base with a SFS front then check off the skin base you want in the dropdown menu and specify in the 'Comments Box' which type of lace and how many inches of lace you want added to the front. Ventilation is the direction that the hair is knotted in. For example, if you want your hair parted on the left side then the ventilation would be with the part on the left and most of the hair going towards the rigth side of the unit (some hair at the very left would go toward the left side). If you order freestyle ventilation then the hair takes no set direction and can be styled in a variety of directions--great for experimenting with different styles.
Regards,
John