Fundraising for transformer headphones, turning from open to closed

An English startup calling itself Trinity Audio Engineering (although it consists of two people), wondered why people have to buy two sets of full-size headphones, open and closed. Is it possible to make transformer headphones that you can customize?
No sooner said than done, and engineers after a year of development came to the largest crowdfunding platform Kickstarter with their project Trinity Vario . These are full-size (they are also sometimes called monitor) headphones that completely cover the ears and allow you to fully enjoy the sound. In this case, by simply turning the flapper located at the rear of the speaker, the headphones turn from open to closed and vice versa.
According to the type of acoustic design, full-size headphones come in two types. Open partially miss external sounds, which allows for a more natural sound. Many well-hearing professionals say that the sound of open headphones is more “transparent and natural” compared to the sound of closed headphones. Another plus of them is that you do not cut yourself off completely from the outside world and can react to sound, for example, warning of danger.
Of course, if it is noisy around you, then it is inconvenient to be in such headphones. And if you like to listen to very loud music, then the sound will penetrate outward, interfering with others. For such cases, closed headphones were invented - they do not pass external noise and provide maximum sound insulation. You can escape from the outside world and completely immerse yourself in the enchanting world of music. Such headphones are sometimes offered an active noise reduction system.
Marketers came up with another type, " half-open " - which supposedly provide sound insulation, and at the same time give a more natural sound.
The developers of Trinity Vario promise that you can easily switch from open to closed headphones by choice. They should be strong enough, because they are made of stainless steel and aluminum, while their weight is 336 grams. Headphones fold for easy carrying. Three exterior designs are presented: dark anodized aluminum, brushed, and polished steel.

Specifications:
- Speakers: 50mm
- Impedance: 42Ω
- Sensitivity: 105 ± 3db
- Frequency: 19 - 21000Hz
- Cable length: optional 1.5 m or 3 m
- Plug: 3.5mm gold plated
Developers collect the sum of £ 100,000, when it is exceeded, they promise to add support for Bluetooth (and as you know, with Bluetooth everything is getting better). For two days of work, the campaign raised £ 13,000.
Headphones themselves are offered as prizes, the cost of which for backers starts from £ 125 (at the ruble exchange rate for tomorrow it is about 13,000 rubles). Two headphones can be ordered for £ 240. The developers plan to establish a retail price twice as large, £ 249. Additional cables will cost £ 10. Deliveries promise to begin in March 2016.
Discussion of the proposal can be found on the specialized site Head-Fi .