With the increased seam length, Goff says there was actually a risk that this ball would be too rough. “Very little changes in those textures can have noticeable aerodynamic effects,” he says. The fact that the Telstar 18 has almost the same drag curve as the Brazuca, with aerodynamic properties changing at about the same speeds, is impressive. “It has to be an engineering and technical challenge,” he says.
On the other hand, replicas (sometimes called training balls or gliders) are designed to be just like the official match balls but are much cheaper. Their panels are often stitched rather than thermally-bonded and are made of a different material. However, they’re not necessarily less durable than official match balls. So, they’re the recommended option for most players. https://www.youtube.com/watch?v=j2Xn84L3Kcs