My new Challenger 37GT came with 2 slide locks, one of each size. The only time they need to be used is if a slide mechanism has failed and the slide won't stay in by itself. The Schwintek motors lock the slide and prevent it from moving. I've never used slide locks and have never had a problem of a slide moving while driving.
Bruce Dickson 2013 Thor Challenger 37GT, 5 Star Tune, Safe-T-Plus Steering Control with Air Trim, Roadmaster front and rear Sway Bars, SuperSteer rear Track Bar, Crossfires, 2018 Honda CRV . Full timers since Jan 2012.