I have been using a neck weight identical to the one shown below for a couple months and noticed something funny today. Per usual I get diaphragm contractions as early as 20m and thought my C02 tolerance/relaxation was very poor. I shortened the leash a little in search of a better fit and less drag at the cost of my shoulders pressing the wrap into my neck and immediately the contractions delayed significantly. This is a 5 lb weight, never uncomfortable and not much for a 180 lb person with a stout neck. It appears the pressure from the narrow strap in the loose state was enough to affect my reaction to CO2. Has anyone else had a similar effect or understand what might be going on?