The subscription includes one volume of the MX Book of New Sherlock Holmes Stories in paperback per month (RRP $24.95). Books are sent out once a quarter to optimise shipping. Each volume includes 20+ traditional Sherlock Holmes stories and the subscription is comes with a $5 discount per volume.
The books build into the largest Sherlock Holmes story collection in the world - with 52 volumes and over 1,000 stories.
(here's a picture from one of the collectors of three more editions and the others on the shelf behind).
The collection has raised over $135,000 for the Stepping Stones School for children with special educational needs based at Undershaw, Sir Arthur Conan Doyle's former home. Over 200 authors have taken part so far including forewords by celebrity authors such as Lee Child and Kareem Abdul Jabar.