Figure 2-20. A) Non-collapsible slider and B) collapsible slider.  Figure 2-21.  Type 1 deployment—T-7A reserve. Figure 2-19.  Quarter bag. and slows down the opening. While other methods have been  developed for military or aerospace applications, the slider is  the preferred method of reefing ram-air canopies. Without this  device, skydiving would not be as developed as it is today. There are currently six different types of deployment  methods, which are listed below.  With this method, the lines are stowed vertically or  horizontally in the container. Examples of this method are the  T-7A chest pack or the B-12 back parachute.  [Figure 2-21] Deployment Types Type 1: Canopy First Deployment  Type 2: Two-Stow Diaper or Half Diaper  and soon became popular for sport parachuting or skydiving.  With the growth of skydiving and the increased use of the  reserve parachute, it soon became obvious that the reserve  parachute needed to be controlled more. In the mid 1970s,  the two-stow diaper was developed for use with emergency  and reserve parachutes. This design was soon followed by  the three-stow diaper and the piglet-style diaper invented by  Hank Ascuitto. During this time period, the deployment bag  became the preferred method of deploying the increasingly  popular ram-air or square canopies. In 1977, Para-Flite, Inc.  introduced the first ram-air reserve canopy, which utilized  the “free bag” deployment system. This design continues  to this day virtually unchanged as the preferred method of  deploying square reserve canopies. Reefing devices slow down and stage the opening sequences  of canopies, resulting in lower opening forces. This is  particularly critical at higher speeds where the excessive  “G” forces experienced may injure or kill the user. The  most common reefing device used today is the “slider.”  [Figure 2-20A and B]  This device consists of a piece of  fabric with grommets or rings at the corners through which  the line groups pass. This restricts the inflation of the canopy  This method utilizes split line groups. Two stows from one  line group lock the diaper, compensated by offsetting stows  of the other line group in the container with the remainder of  the lines stowed in the container. Examples of this method  are the early Strong 26' Lo-Po and the Pioneer “K” series  reserves.  [Figure 2-22] 2-12