The Pulse 4 has a rounded cylindrical shape and measures 8.2 inches tall by 3.8 inches in diameter. It’s heavier than your average portable speaker, weighing 2.8 pounds. It’s available in black or white, but the real star of the show is the interior LED panel that wraps around the speaker enclosure’s midsection. The top grille projects audio from a single 2.25-inch, 20-watt driver, and the lower panel (on which the speaker stands upright) houses a passive radiator and is elevated slightly above the surface it sits on. The entire construction has an IPX7 rating, which means it can be submerged in water for up to a meter, allowing you to use it outside or by the pool. Various controls are arranged around the top ring of the speaker, including power, Bluetooth pairing, volume up/down, and play/pause buttons. A button controls the LED lights, and a PartyBoost button connects the speaker to other Pulse 4s to form a stereo pair or a multi-room system (with up to 100 speakers). A USB-C port near the bottom is only for charging; a cable is included. The Pulse 4 lacks speakerphone functionality, which is surprising given its small size and portability—you’ll handle incoming calls on your mobile device. There is also no aux input; it can only be used to stream audio. This exclusion is undoubtedly beneficial to the IPX7 build, but it is an omission that will irritate some users. The JBL Connect app lets you control the LED lights, switch to PartyBoost mode, or set it to Stereo mode (where it syncs with another Pulse 4 to become left/right speakers). These are useful, but the app lacks EQ, which appears to be a missed opportunity. JBL estimates battery life to be around 12 hours, but your results will vary depending on volume levels and how the LEDs are used. Even as a gimmick, the Pulse 4’s light show is impressive. Colors blend and bleed into one another in a natural way. Even if the audio doesn’t always match what you’re seeing, it’s still entertaining—the colors themselves are a mix of neons and pastels, glowing and changing. There are numerous patterns available. The easiest on the eyes look like an animated mash-up of bright Nike colors and the edge of a Rothko painting. Other patterns include tiny dancing dots that explode, rejoin, and change direction, or what appears to be a color-coded graphic EQ that dances to the rhythm and is blurred for effect.