I have an Intermediate Isaac Head and Neck Restraint System.  It has never been installed and all in it's original packaging.  We bought it for our son and then he stopped racing.  Information about the system is below, and you can click on the link to learn more about the system.

The system is now being sold for $895.  We are selling it for $400, OBO!

Don Blockhan
donbccinc@comcast.net
Cell: 206-730-2590

GENERAL INFORMATION:
Isaac systems establish a connection between the head and the shoulders. Actually, they connect between the helmet at one end and roll under the shoulder harness at the other end. The driver does not "wear" an Isaac® product, it becomes part of the harness system. Helmet connections are made with quick release pins so Isaac® can be used by any driver having a set of helmet mounts. Extra helmet mounts are available separately and are installed by the user. The system can be easily moved between vehicles. The Isaac® shock absorbers are custom designed and manufactured to specifications established after multiple computer simulations and laboratory crash tests. The Isaac® Link system uses mil spec parachute webbing rather than a shock absorber assembly.

http://www.isaacdirect.com/index.html