When sourcing these items, the choice of material directly impacts the product's lifespan and perceived value. For Acrylic Keychains, ensure they are made from high-transparency, virgin grade PMMA to prevent yellowing over time. For Metal Keychains, prioritize Zinc Alloy with electroplating (such as nickel or chrome) to ensure corrosion resistance. The insert window should feature a scratch-resistant coating and a secure snap-fit or screw-in mechanism to prevent the photo from falling out during daily use.