This head is called inverted napa and they are great! The head has 2 layers. The layer on top that you hit is plastic and the second layer inside is napa. The sound is a nice aggressive attack but without the overtones and tinnyness of heads that only have the plastic layer. The napa muffles it a little keeping the sound nice and warm.
This style of head with plastic on top with napa inside is reverse from the usual napa heads. Normally you hit the napa outside layer but these are prone to breaking over time. It compounds the problem if the player does not hit the drum squarely!
These heads are waterproof! Great for rainy weather!
I am constantly impressed with the high quality of Timbra's instruments and accessories. They know what they are doing in their factory in São Paulo. All of their drum heads are made by hand and quality tested. Their heads are all tested for material thickness, tension, and pressure so that their heads are consistent.