Dualminer USB Miner

Specs:
- Algorithm: SHA256 (Coins Mined: Bitcoin, BitcoinCash, Peercoin, etc.) and SCRYPT (Litecoin, Dogecoin, etc.)
- Hashrate: Dual mote: 500 MH/s SHA256 and 40 KH/s SCRYPT or 70 KH/s SCRYPT
- Chip: 55nm Gridseed GC3355
- Power use: Dual mine at 2.5 watts or SCRYPT only at 1.5 watts.

The Review:
The Dualminer USB Miner is an interesting miner, featuring a single 55nm Gridseed GC3355 chip capable of mining both SHA256 and SCRYPT coins, using a dip switch to switch between either SCRYPT only (Up to 70 KH/s) or SCRYPT and SHA256 (Up to 40 KH/s SCRYPT and 500 MH/s). However, regardless of which you use to mine, at today's difficulty, you'll make about 5-6 cents a year if you don't have to pay pool fees or electricity. In other words, this miner is not profitable at all, and is more of a novelty/collector's item. It's not too hard to set up like most other USB miners, and can be a nice introduction to how mining works. If you're looking to profit from cryptocurrency mining, I would highly recommend looking into a more modern miner such as Bitmain's Antminer S17 series. However, keep in mind that those machines are significantly more expensive and can use hundreds of times the electricity of a USB miner like the Dualminer.
This miner was released in early 2014, and is completely silent as it does not have a fan. However, I highly recommend a fan for this device, as it can get extremely hot and may cause damage. For optimal performance, I would recommend using a powered external USB hub. Dualminer USBs have not been produced for over half a decade, and can occasionally still be found on online retail sites such as Amazon and eBay, but for a pretty expensive price.
Personally, I have only ever had two of these devices: One from the first batch of production and one from a later batch. The first batch production suffered various issues including the miner stopping mining randomly or just having troubles connecting. However, later batches worked very well, had a very steady hashrate, and submitted few stale or invalid shares. My personal miner actually mined at closer to 80 KH/s on SCRYPT only, and could reach about 45 KH/s SCRYPT and 550 MH/s or more on SHA256 in dualmining mode.
Disclaimer:
I am not in any way affiliated with Bitmain, Dualminer, Gridseed, or any other crypto/crypto-related company. I personally have two of these miners purchased from a retailer in 2014. The first batch miner stopped working just months into use, and has since been collecting dust in a box. The second miner from a later batch continued to function until I replaced it on my USB hub with a Gekkoscience 2PAC. It is still functional today, but I simply don't use it due to its incredibly low hashrate by today's standards.
Remember, investments in cryptocurrencies are like any other investment: Invest only what you can afford to lose. No investment is a guarantee.