Sorry, had to leave before I finished my thought:
How they work:
When you tighten "snug" the bar in, you are not "holding the slide in;" you are rotating the slide inward and down, pre-loading the clutch in the pinion gear so it does not unlock.
That is what keeps the slide from moving. There is no way (due to mechanical advantage) to turn the motor with the slide. So by preventing the overload device (spring loaded pinion) from moving away from the rack you essentially lock the slide in place.
Again, not saying YOU have to use it (just WHY you should). Many folks here think that because some of us are proponents of using safety devices and following posted limits on our camper and truck that somehow we are "girly men." Maybe they are right, but there it is...
Color me "weight police," "safety glasses police," and "safety bar police."
Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW