Speaking technically, let's start by looking at some specifications.
Output power: 50 m/w
Speaker dimension: 36mm
Cable length: 1 meter
Jack: stereo mini: Yes
Frequency response: 60-20,000Hz
Pick-up pattern: N/A
Weight: 'about the weight of a sweatband'
Connectivity: Stereo mini
Active noise attenuation: 50-1500 > 10dB @ 300Hz (ambient noise filter)
Technically things are pretty standard with a small but reasonably sized speaker for each ear (36mm) and the use of the fabric sweatband to actually en-close the speaker.
To be frank, I cannot believe someone has not thought of this before now, especially given how often small ear buds fall out and how bulky full sized headphones could be while working out.
So, it's top marks for innovation then. I actually looked out the window and saw a young girl jogging by wearing the Halo headphones yesterday. So we can be sure the marketing team is functioning well, too.
In all honesty, when I saw them being used, albeit vicariously in the environment they have been designed for, I thought that is really not a bad idea at all.
So, I think the main focus of this particular review is really on the ease of use and function of what is undoubtedly a fledgling product which I am sure will be taken back and forth to the drawing board numerous times as demand and interest spike over the coming months; possibly even years.
Now, regarding the specifications of these headphones, the only real figure of interest here is the 'active noise cancellation' which one thinks would provide a hardware based filter which acts between 50-1500Hz with as much as 10dB of attenuation at 300Hz.
Basically, noise cancellation is something designers of headphones have been trying to perfect for some time. I think some companies have even perfected the art these days, but at some considerable expense to the buyer. But it's nice to see some effort being made here to include a feature not seen of headphones costing several times the price.