So, I got these 5.25 inch speakers for the two front seats of the car. They definitely don't sound like component speakers, but they are quite satisfactory. Their volume is good but not perfect, the same goes for the highs and their bass. But for 50 euros, they are great. Maybe the component speakers are worth more, but if you want them for a quick fix without very high expectations, they are very good

I don't know what expectations some people have with 50 euro speakers, I am extremely satisfied in my 2003 Hyundai Accent. I had them installed in the two front doors and they have an incredibly strong sound and relatively clear for their price!!! Kudos to Hertz

I replaced the old factory Pioneer speakers I had in my Toyota, clearly better performance even at high volumes, clearer sound, and a click better bass. The source is Alpine and the door has extra sound insulation, I am very satisfied (I don't have crazy expectations from sound in the car and intentionally don't have an amplifier). It comes with a very detailed instruction booklet, screws, and brackets.

Unfortunately, minimal improvement compared to the factory 20-year-old worn-out speakers that the car had. My opinion is that these play like a replacement for the factory ones and not as an upgrade. I suggest that anyone who wants to upgrade should look for other, possibly more expensive, options.

They were installed in a Hyundai Accent 2004. I was expecting a bigger difference from the stock speakers. Nothing impressive, just slightly better sound than the stock ones. And I don't know if there is anything better in these dimensions.

Very bad sound separation, the bass is lost, as well as some sounds. They distort at high volumes.

Replacement of the rear factory speakers (made in China) in Fiat Grande Punto 2006. Phonocar bases with code 03920 are required for their installation for this specific car model. It was necessary to carefully bend down and back the 4 ears in order to screw them correctly with shorter screws than those in the package on the side of the base. Excellent result, satisfactory sound.

Whatever applies to the 100.3 also applies here. The bass is a bit dry due to its size, but it's worth it. They are played with a weak power source (4×17watt), but due to their high sensitivity, they can play loudly and clearly. A significant upgrade compared to the factory speakers (yaris). I have listened to other branded speakers with the same peak wattage (not RMS), and none of them played like the Hertz. With a larger power source, things might have been different, but in my combination, it was just right. A solution for the bass would be an active subwoofer. When I find the time to install it, I will write my impressions.

I bought them for 38 euros including shipping, for the rear doors (in MEGANE sedan 2003).
They fit perfectly in the slots.
For this price, I don't think there are better speakers.
I give 4 stars because I also bought the detachable Hertz DSK 130.3 for the front and the difference in quality is huge, but the price of the detachable ones was almost double (59 euros).
Anyway, to tell the truth, even the front ones wouldn't sound so perfect without the help of the rear ones.
Perfect pair.
Video: https://youtu.be/zKbLOAQfVKU

Edit: I now use the Alpine UTE-200BT as a source and the sound is amazing.

(However, the Alpine UTE-200BT lacks in Bluetooth connectivity and microphone sound, the cheap Osio ACO-4530UBT that I had is much better in Bluetooth.)