Fusion hair extensions (also known as bonding or pre-bonded or keratin hair) are fused to natural hair using different adhesives such as glue. Applying pre-bonded hair extensions take approximately 3-4 hours to apply and are also applied by a hairdresser. The application involves a machine that looks like a hot glue gun, which essentially glues the hair to individual strands of the natural hair. Another type of application for pre-bonded hair extensions uses a heat clamp to melt the glue to the natural hair.
Fusion/pre-ponded/keratin hair application is managed and treated the same way as your real hair. You can use the same products you would normally use, however, the extensions need re-positioning every 2–3 months as the natural hair grows.
They are considered semi-permanent as they stay in your hair for up to 4 months. However, like all other types of hair extensions, this varies based on your own hair type and growth.