(We don’t know when you’d ever need that number, but it’s there.) Similar speakers like the Ultimate Ears WONDERBOOM and Polk BOOM Swimmer Duo have similar capabilities, but only JBL has the app that can network more than 100 devices. If you have more than one Charge 4, you can use the JBL Connect mobile app to network them together. You can expect this speaker to stand up to the elements, endure heavy usage, and last all day. This was great when we took it to the beach since it allowed us to extend our time by the waves without our devices dying. The speaker’s back panel includes a USB port that you can use to charge smartphones and other devices. We also found the charging bank to be very convenient. The male-to-male charging cable has a USB-C connection on the speaker end and USB to connect to the power supply. You can tell this is a next-generation device due to its charging cable, which utilizes the relatively new USB-C technology. (And if you charge it overnight, it doesn’t really matter anyway.) That’s still on the longer side for charging time, but this should be expected considering the Charge 4’s battery capacity. It took our test unit about four hours to go from completely dead to fully charged, which is 90 minutes faster than JBL advertises on the included materials. It not only gives you a general idea of how much juice it has left, but also indicates its charging progress when the speaker is plugged in. The battery meter is one convenient feature on the JBL Charge 4 that isn’t found on many other speakers. We took this speaker on a road trip to the beach and let it play constantly throughout the day and it never quit. JBL claims the Charge 4 gets 20 hours of battery life, which is definitely on the long side compared to similar products. Unfortunately, there’s no way to skip to a previously-played song with the speaker’s control panel. You can control the volume of the speaker and skip songs either from the speaker itself or the device it’s paired with. It costs less than you would expect for the quality you get.