Most French press-on nails are made from ABS plastic; some sets use high percentages of post-consumer recycled plastic, and a few are made from 100% cured gel rather than traditional plastic.
Many sets include multiple sizes to improve fit—examples in listings show offerings with 12, 16 and 21 sizes—and several products note engineered or inclusive sizing so you can match nails to your fingers.
Adhesion options include traditional nail glue, pre-applied peel-and-press adhesives, and adhesive tabs for quick, no-glue application.