Standard sliding strap systems use traditional tri-glide buckles to adjust chin strap length—the same simple design found on most helmets across all price points. You thread the strap through the buckle and it holds by friction. It's straightforward, easy to understand, and adds no extra cost to the helmet.
The trade-off is that these straps can slowly slip over time, meaning you may need to retighten them every few rides. It's not a safety concern if you check your fit regularly, but it can be annoying if you're someone who likes a set-it-and-forget-it setup.
For casual riders or those on a budget, standard sliding works perfectly fine. If you ride frequently or find yourself constantly fiddling with loose straps, adjustable splitters with locking are worth seeking out. Regardless of which system you have, always ensure your straps form a V directly below your earlobes and that you can fit one to two fingers between the chin strap and your chin.