In the mid to late fifties the Hartley single cone 10" MS220 was placed in a modified infinite "boffle", correctly spelled as mentioned, and it was touted to have a performance between 20-20,000 Hz. They were demonstrated with a demonstration record which began with a drum roll and it was an effective sales tool. The speaker had a very good mid-range and because of this, it was a stellar performer which sold quite well. This period is also the same period where the Wharfedale W12FSAL was also promoted as a full range 12" speaker. It, too, was a remarkable speaker and I have recently purchased a pair and I am presenlty astonished as to how a 12" speaker can produce such highs. Both speakers had a foam surround and when you find them they do need to have those surrounds replaced.
These are interesting speakers which give credit to their designers for that time period in the music reproduction history. As such, there are many who are presently seeking these speakers as collectors items. They are not on a par with current speakers, but they are a credit to their designers who relied solely on their ears as their instruments for judging their merits.