As always with Nike balls, the Merlin has an excellent feel, particularly when passing. The ball is also great for shooting due to Nike’s 4-panel construction, 360-degree sweet spot technology and the soft polyurethane outer material. It won’t deviate too much in the air due to the thermally-bonded pentagonal panel layout, so it’s perfect for training as well as games.
At the World Cup level, these tiny changes in a ball’s aerodynamics can legitimately impact a team’s performance, so the intense scrutiny of the World Cup ball is perhaps to be expected. “You could argue that it’s the most important piece of equipment in the most popular sport in the world,” says John Eric Goff, Professor of Physics at University of Lynchburg.
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