The problem of back strap slip is not universal, some people do not experience this problem at all, yet for some they cannot keep the head gear in place for any length of time. One of the main reasons for this big difference, is a physical feature, it is not just a subjective feeling. Compare the normal variation in the head shapes of the two profiles below.
The second one does not have the slight back bulge which the first one does have. Most normal head gear's back strap simply will not stay in place if your head shape is closer to the second one. When somebody here posts a problem with the strap slipping another person (with the first profile) would vehemently instruct to keep that back strap below the mid point --- but it is not going to help for the second profile at all . When you are in a group if you look around you would find that this second variation in head shape is not all that uncommon, about one in 5 has this shape.
This fix here is similar to the one I have described earlier for the Aeiiomed Headrest mask at:
viewtopic.php?t=33486&highlight=
However, the head gear of the Headrest is a rather uncommon form. The head gear of here for Swift LT, is similar to many other model masks'. I describe the construction here very briefly, those who need a bit more of detail, please see my above post.
I use about 20" length of 3/4" wide elastic attached to the back strap, and secured in place as a chin strap with a small chin strap pad. Since Swift LT is a very light mask, you can keep that in place with very little tightening of this elastic, it can be really light.
The elastic (black) is looped through the inside back strap loops near the back buckle. The ends are attached with velcro strips, to the chin pad. The two ends both have the sticky type of the velcro (white), whereas the beige chin pad has the non sticky type of the velcro (black strip) sewn on to it. I used white and black velcro just for clarity in the photo, normally when you buy both will be of the same color.
The above particular way of using the velcro (the sticky portions are very small, but still a lot of length for adjustability using the longer non sticky velcro on the pad) reduces the unwanted tangling up of the velcro. Also this makes it easiier to just remove the chin/mouth pad for washing.
The above shows a close up of how the elastic is threaded. It is extremely easy to do. You may want to attach the elastic to the head gear strap at the loop, with a staple or a small stitch, so that it won't slip out.
Once you put on the head gear as usual, after checking/positioning it for comfort and no leaks, the new elastic strap ends are brought around the neck, below the ears, and then attached to each other in front of the chin. I use this to lightly go over the light masking tape over my mouth to prevent mouth leaks. Again my elastics are very thin, and only lightly attached, that if I simply pull up on the back strap I can still remove the whole head gear and mask without first having to undo the elastic in the front (such as when one may want to sneeze or cough in a hurry). Normally, I undo the elastic strap in the front and the remove the head gear as usual in the morning.
If you have any questions about how it is done, feel free to ask questions. Hope this helps some of you with head gear slipping problems.
