A rubberized elastic band is a wide band that wraps around your leg with a rubberized interior surface that grabs onto your skin or base layer. It's the most secure grip system you can get, which is why it's typically found on race and high-performance pads. If you're charging hard, racing gates, or taking big falls in the park, this system keeps your pad locked exactly where it needs to be.
The downside is comfort. To do its job, the band needs to fit snugly, which can feel tight over a full day of skiing and may leave temporary marks on your skin. It's also less forgiving if you're between sizes.
For most skiers, silicone grips offer plenty of security with better all-day comfort. But if you absolutely cannot afford to have your pad shift during a fall, the rubberized band is the way to go.