Selections allows you to purchase 2,500 sqkm of OS Explorer (1:25,000) mapping data in an area you specify graphically using a "route". I have used it for several years and found it useful although you do have to wait a couple of weeks for your data to arrive on a custom CD.
Please be aware that since March 2012 Memory Map are no longer honouring the data promised in this product.
The web page[...] where you send the information required is no longer functioning (although it appears to work and you do get a confirmation page) but no follow-up email is sent.
When nothing arrives after the specified 14 days and you contact customer services they may offer to give you an equivalent credit on their new Digital Mapping Shop (DMS) but be aware that this is in an incompatible format (.qc3) to that produced by using Selections (.qct). You can see maps in either format in the software but not both together if they are adjacent regions. If you are happy to use the new data format, you would be better going direct to DMS and buying credits there or from other (discounted) sources. The data is downloaded direct to your PC so there is no wait for a CD.
Addendum: Memory Map relented and provided the data in .qct format but the equipment they use is soon to be decomissioned so they just won't be able to offer the service very soon.
plus - for anyone who wants to see an Ordnance Survey map (or a French IGN map) on their computer, this is a great product to have. minus - these maps work out so expensive
I must admit to being a bit of an addict to these maps, have got quite a collection now. Memory Map supplies its own PC application to view the maps, which is decent enough. You can also print them off etc. and export them to certain (but note not all - best to check Memory Map's site) devices. Most notable inclusions include Windows Mobile devices (which I have experience of) and iPhones (which I don't). Notable exclusion was a Garmin Edge cycle computer (a shame because that would have been great on this device which has an inbuilt gps).
You need to be careful when looking at Memory Map's site because when they talk about compatibility, I think they're quite often talking about routes, not the maps themselves.
Worth shopping around for these "selections" products too - at the time I bought this I found Amazon probably around half the price of some other vendors.