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We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
If you want a wired, volume-limited pair of 40mm driver headphones built specifically for a child to carry to school every day, choose EarFun K3; if you need one wireless bundle that covers over-ear listening, workouts and room-filling sound in a single box, choose Memorex 3-in-1.
• EarFun K3 — biggest strength: a wired USB-C connection with a built-in volume limit and a 40mm dynamic driver, aimed squarely at kids and school use.
• EarFun K3 — biggest trade-off: it is wired only, so it needs a USB-C port on the device (and it will not work plugged into a USB-C charging port).
• Memorex 3-in-1 — biggest strength: three wireless products in one pack — over-ear Bluetooth headphones, true wireless earbuds and a portable speaker — all on Bluetooth 5.1.
• Memorex 3-in-1 — biggest trade-off: every piece depends on a charged battery, and the headphones are rated at around 4 hours of playtime, so it is not a grab-and-go wired solution.
• Pick EarFun K3 if the buyer is a kid, a parent or a school, and the priority is durability, safety limits and zero charging.
• Pick Memorex 3-in-1 if the buyer wants flexibility — one purchase that covers commuting, workouts and shared listening at home.
The EarFun K3 is a kids' over-ear headphone with a 40mm dynamic driver, a 20 Hz – 20,000 Hz frequency range, 32 ohm impedance, 100 dB sensitivity and a wired connection over an upgraded USB-C connector. In plain terms, that is a full-size driver in a child-sized shell — the same driver diameter you see on plenty of adult headphones, which is why it can produce proper stereo sound rather than the thin, tinny output of cheap toy headphones. The 32 ohm impedance and 100 dB sensitivity also mean it does not need a powerful source; a tablet, a Chromebook or a school PC will drive it without trouble.
What it does best is survive. The build uses ABS plastic with recycled and eco-friendly materials, and the whole thing folds for transport. There is a volume limit, which matters a lot if you are handing a headphone to a young child, and the over-ear fit plus 207.9 g weight is in the range most kids can wear through a lesson without complaining. The USB-C connector is the smartest part of the design: it matches the port most modern tablets and Chromebooks already have, so there is no dongle to lose and no battery to remember to charge. EarFun backs it with an 18-month warranty.
Who should buy it: parents of kids and teens, teachers and schools kitting out a classroom of tablets, and anyone who wants a wired headphone for a child that will not run flat mid-afternoon. It is also the better pick if the child is rough on gear, because there is no battery, no pairing and no charging case to break.
Memorex 3-in-1: Who It's For
The Memorex 3-in-1 is not really a headphone — it is an audio kit. The bundle contains three separate products: over-ear Bluetooth headphones with a 40mm driver unit, a pair of true wireless earbuds, and a compact portable Bluetooth speaker. All three run Bluetooth 5.1, with a stated range of about 10 metres, and the box includes USB-C charging cables, spare earbud tips in S/M/L and three user manuals. The colour is blue, the headphones use a fabric-and-rubber finish, and the warranty runs for one year.
The headphones themselves are the direct counterpart to the EarFun K3 on one spec: a 40mm dynamic driver with a 20 Hz – 20,000 Hz frequency range. So both products share the driver size that this whole comparison turns on. Where they diverge is everything around it. Memorex's headphones are wireless, with soft padded ear cushions, an adjustable headband, a 90-degree rotating design and a foldable structure — all useful if you want to fold them flat in a bag. The trade-off is battery: the headphones are rated at roughly 4 hours of playtime at 50% volume, with a 4-hour charge time. That is a short leash by modern standards, and it is the number I would weigh most heavily if you plan long listening sessions.
The earbuds are the endurance piece of the bundle, with up to 7.5 hours of playtime at 50% volume, touch controls for play, pause, skip and volume, a built-in mic, and three ear-tip sizes for a secure fit. The speaker adds Bluetooth streaming, a built-in microphone for calls, USB, TF and FM inputs, and a rechargeable battery — the piece that makes this bundle genuinely useful for a picnic, a kitchen or a hotel room.
Who should buy it: someone who wants one purchase to cover several jobs — wireless listening on the move, earbuds for the gym or a run, and a speaker for shared music. It is also a reasonable pick for a household where different people will grab different pieces. The age range is listed as all ages, and the touch controls keep the earbuds simple to operate.
Side-by-Side: Which Should You Choose?
• Best for young kids and school use → EarFun K3. Volume limit, wired USB-C, no battery to manage.
• Best for flexibility and multiple use cases → Memorex 3-in-1. Headphones, earbuds and a speaker in one pack.
• Best for battery life → Memorex 3-in-1's earbuds, at up to 7.5 hours at 50% volume. The over-ear pair is the weak link at around 4 hours.
• Best for never thinking about charging → EarFun K3. It is wired, so it works the moment you plug it in.
• Best for shared listening → Memorex 3-in-1, because of the portable speaker with hands-free calling and USB/TF/FM inputs.
• Best for durability against rough handling → EarFun K3, built from ABS with recycled materials and an 18-month warranty.
• Best for gym and running → Memorex 3-in-1's TWS earbuds, with touch controls and three ear-tip sizes.
• Best for device compatibility → depends on your port. EarFun K3 needs USB-C audio; Memorex 3-in-1 needs Bluetooth 5.1 and a charged battery.
In my opinion, these two are not really competing for the same buyer, which is exactly why the choice is easy once you know the job. If the person using them is a child, or if the headphones will live in a school bag and be plugged into a tablet, I would buy the EarFun K3 — the volume limit, the wired USB-C connection and the 18-month warranty make it the more responsible and lower-maintenance pick, and the 40mm driver gives it real sound rather than toy-grade audio.
If instead you want one purchase that does three jobs and you do not mind charging things, I would buy the Memorex 3-in-1. The 40mm headphones match the EarFun on driver size, and the earbuds and speaker are the parts that make it feel like good value for a household. Just go in knowing the over-ear pair is a roughly 4-hour device.
Check the current price on Amazon before you decide — that is the one number that can genuinely break the tie.
FAQ
They are the electro-mechanical engine that turns an electrical signal into sound. A 40mm dynamic driver uses a diaphragm and voice coil, and the frequency range on both of these products is quoted as 20 Hz to 20,000 Hz — essentially the full span of human hearing.
There is no single best size. Bigger drivers can move more air and often deliver stronger low end, while smaller ones suit compact earbuds. What matters more is the tuning and the seal around your ear. In my opinion, a 40mm driver is a sensible sweet spot for over-ear headphones, which is why both of these use one.
Yes — it is a solid, mainstream choice for over-ear models. Both the EarFun K3 and the Memorex 3-in-1 headphones use a 40mm dynamic driver, and both quote the same 20 Hz – 20,000 Hz range, so the real differences between them come down to wired versus wireless, the volume limit, and battery life, not the driver.
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