This is one of the lowest prices we've seen for an unlimited 12 month data contract, and will save you £24 a year on the £20 per month deal Three launched ahead of its 5G rollout.
If you don't mind committing to a 24 month contract, Three also has another killer offer for Cyber Monday. For the first six months, you'll only pay £10 for unlimited data, minutes, texts and 5G. The remaining 18 months will cost £20 per month - which is still quite a reasonable deal. Head over to Three for this bargain.
Three expects its 5G to be up and running in 25 towns and cities before the end of the year, and the great news is that this plan is 5G-ready at no extra cost. To take advantage you will need a supported phone, but your existing 4G device should be more than fast enough on Three, particularly with its estimated 99.8% coverage.
As one of Three's Advanced Plans, this will also get you access to Go Roam Around the World, meaning you can still use this data in 71 global destinations at no extra cost.
Personal Hotspot is also here, so you could even use the 4G signal to replace your home broadband.
Superdrug also offers unlimited data for £20 per month, but this gets you £20 worth of loyalty card points upon sign-up and double points on your shopping throughout the contract. SMARTY, owned by Three, is offering the same deal for £22 a month, although its USP is usually that it will buy back the data you don't use.
Both these companies use's Three's network as a 'piggyback' provider, so you'll be getting the same service whichever one you choose.
Alongside EE, O2 and Vodafone, Three are one of the four main phone networks in the UK, with all other providers buying space from them. This shouldn't affect the quality of service you receive though, regardless of who you go with.
Check out our round-up of the best SIM-only deals.