Based on this product's specifications, here are some alternatives and similar models
Adjustment Dial for GIRO Merit RL TRL Fit System helmet, black, size S
Summary description:
Replacement adjustment dial designed for GIRO Merit RL TRL Fit System helmets. This black size S dial fits the Merit RL TRL retention mechanism to restore or fine-tune helmet fit. Intended for use as an original-equivalent spare part to adjust head circumference and secure positioning for everyday cycling and commuting.