Our take
GN21B-GRAY is a compact USB-C hub for someone who needs two USB 3.0 ports, SD and microSD readers, and a DisplayPort path through USB-C. The model-specific source distinguishes it from HDMI-equipped HyperDrive siblings. Its port mix is useful, but the saved material does not establish DisplayPort refresh rate, PD wattage, or a current Amazon mapping.
A USB-C host user who wants two USB 3.0 connections and removable-card access and can confirm its DisplayPort path with the computer..
Not for a buyer who specifically needs HDMI, a confirmed 4K refresh rate, or a documented laptop charging wattage without checking the exact host and listing.
Pros & cons
What could work for you, and what to consider before buying.
What works in its favor
- Best Buy names GN21B-GRAY and lists two USB 3.0 ports.
- Both SD and microSD readers are included in the described port set.
- The USB-C port is documented for Power Delivery and DisplayPort capability.
What to weigh up
- Video is DisplayPort over USB-C, not an HDMI socket.
- The saved source does not give the DisplayPort refresh rate or PD wattage.
- Historical ASIN B01LSIZI7W was not mapped to the verified model.
Specifications and exact model details
The key details
| Model covered | GN21B-GRAY |
|---|---|
| Host connector | USB-C host; verify the computer supports video over USB-C |
| USB 3.x data ports | Two USB 3.0 ports; backward compatibility with USB 2.0 devices is listed |
| Installation | Portable five-port hub with DisplayPort-over-USB-C rather than HDMI |
| Hub power | A USB-C PD connection is listed; wattage is not established |
| Host charging | Host-delivered charging and DisplayPort refresh behavior are unknown |
Performance figures are manufacturer claims. Source checked October 5, 2026. Regional models and included accessories can differ.
Full review: how the features affect your choice
What the features mean for you
Choose the model for its USB-C DisplayPort path
Best Buy identifies GN21B-GRAY as a five-port USB-C hub. Its described set includes two USB 3.0 ports, a USB-C connection with Power Delivery and DisplayPort capability, and SD and microSD readers. That is a compact mix for a compatible laptop that needs ordinary USB peripherals and removable-media access along with external video. The output is DisplayPort over USB-C rather than a separate HDMI port, so it will not suit a buyer who needs an HDMI socket without an additional adapter.
Check video support on the host before connecting a monitor
The saved Best Buy feature copy lists DisplayPort over Type-C up to 4K. It does not state a refresh rate, so the profile does not promise 4K60 or even a particular mode beyond the listed resolution ceiling. The computer's USB-C port must also support video output. Check the laptop's capabilities and the monitor input before relying on this hub for a specific display. Similar HyperDrive names include different HDMI-equipped variants, which makes the full code especially important when comparing photos or sellers.
Use the two USB 3.0 ports for documented data expansion
The source lists two USB 3.0 ports and backward compatibility with USB 2.0 devices. That provides a clear minimum for a buyer with a mouse, keyboard, or a couple of USB accessories. It is not a promise of sustained 5Gbps transfers under load, and the saved material does not report a measured rate. Keep that distinction in mind if a large external drive is central to the setup. The profile does not invent a dedicated USB 2.0 port: backward compatibility is not the same as a separate USB 2.0 socket.
Confirm charging needs separately from the video feature
A USB-C Power Delivery connection is listed, but its input wattage and the amount delivered to the host are not specified in the saved product information. A buyer should compare the current manual or seller label with the laptop's charging need before relying on pass-through. The presence of a PD-capable port alone does not establish that the hub will provide a particular power level. Keep the product's video path and charging path as distinct requirements rather than assuming one claim proves the other.
Keep the GN21B-GRAY variant and historical row distinct
The model code is supported by a Best Buy listing and a matching regional Hyper description. Historical Amazon ASIN B01LSIZI7W was unreadable and is not mapped to a current exact offer. Use a tagged search for GN21B-GRAY, then compare the seller's port diagram for DisplayPort-over-USB-C, two USB 3.0 ports, and both card slots. Do not merge it with a similarly named model that has HDMI. This summary uses saved product descriptions and makes no current availability or hands-on performance claim.
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Before you buy
Does GN21B-GRAY have an HDMI socket?
No. The saved model record describes DisplayPort over USB-C, separate from HDMI-equipped variants.
What 4K refresh rate is verified?
The source lists DisplayPort up to 4K but does not establish a refresh rate.
Is its historical Amazon ASIN confirmed?
No. B01LSIZI7W was unreadable and remains unmapped to GN21B-GRAY.
Where can I check the current price?
Use the Amazon link for current offers. Check the exact model, seller, product condition, delivery, and return terms. This page does not display a live price or confirm stock.
Sources and review basis
Sources & review basis
We use the linked product documentation for the features above. Our suitability notes and buying advice are editorial judgments based on those features, not measured performance results.
- Best Buy HyperDrive GN21B-GRAY product record, cross-checked against Hyper regional description ↗ — checked October 5, 2026.
- Best Buy identifies GN21B-GRAY and lists USB-C PD/DisplayPort, two USB 3.0 ports, and card readers ↗ — checked October 5, 2026.
- Regional Hyper description corroborates the GN21B feature family and five-port layout ↗ — checked October 5, 2026.
- Historical ASIN page was unreadable and is not mapped to current GN21B-GRAY offer ↗Paid link · We may earn a commission. — checked October 5, 2026.
Is it the right fit?
Check the exact model and today’s offers on Amazon.