In some vehicles, it is an option to mount the retractor of a seat belt using the rear parcel shelf as the anchoring structure. The belts are a lap sash style of belt (see adjacent diagram) with a few differences to “On Pillar “ or “In Pillar” models.
Parcel Shelf belts do not use a sash guide (the flat loop pillar fitting that creates the sash part of the belt). Instead they are mounted and orientated such that the position of the retractor itself determines the angle of the sash. There are only two variations of parcel shelf mounted retractors. Both must be mounted to a horizontal surface and generally service rear seat passengers. Also note that Parcel Shelf seat belts are "reverse wind" type.
“On Parcel Shelf” is the term used to describe a belt whose retractor sits on top of the parcel shelf. The relevant and only angles that these may be positioned at are 0º to the direction of the vehicle and 0º to the floor of the vehicle. They are known as “0/0 belts”. They are supplied with a plastic cover to protect the retractor.
“Under Parcel Shelf” describes a belt whose retractor is mounted underneath the parcel shelf. These belts are exactly the opposite of the “On Parcel Shelf” and are therefore termed “180/180” belts.
For more information on Parcel Shelf Horizontal Mount seat belts click here