You can't go out to practise trial if you don't have a trial jersey. It's as simple as that. You need a good upper garment and, together with the pants, the jersey will form part of your most basic attire. And if you're a trial professional, all your sponsors, modest as they may be, will agree that you have to get the best possible jersey.
Currently, the best manufacturers like, for example, Hebo, work with resistant fabrics that are also breathable. Today's jerseys have good detailing such as Lycra collars for a softer feel against our skin or elastic micro-cuffs for a better hold of the garment to our body. It's enough to incorporate some protections to finish off the outfit.
They come in all colours, even printed with the brand of your bike, and sizes, including children's ones. Because trial is one of the best modalities to get our kids initiated in the bike world!
Finally, if you're someone who prefers to have the jersey and pants as a single piece, you have the 1 piece trial suits available as an alternative.