From their announcement:
Chapterhousestudios.com has announced the release of some awesome head bits that look perfect for Ymargl Genestealers.
We started working on the concept for these pieces last year, they can also be used as Cthuhlu heads. They are done in time for ‘Nid players to add some variety to their bug models. These were sculpted to customize 28mm models, and look great on genestealers.
The kit is composed of 6 heads, you will receive 2 copies of 3 different sculpts. Each pewter kit is available for a low price of $5.25 (about $.88 a head, plastic bits cost more then this).