Warriors line of heads with Titanium inserts meant to help the head retain it’s shape.

Brine Edge Ice clear plastic head that was very easy to break.

STX Liquid with the throat plug and floating sideway.

Gait had a line of shafts that were position specific, i.e. a face-off handle, a goalie handle, etc… based on the db803 each with a unique combination of a permanently (supposedly) attached sleeve with a textured grip.  The shafts were the same other than the lengths and the combination of grip designed used.  They tried to bring these to market for about 3 years before giving up.  I think only 1 of the 4+ design ever was made available for sale and only in small qualities.

Gait Oracle this wasn’t as outrageous as other failed innovations on this list, but the Oracle featured a number of patented innovations for Gait.  Gait put as many of these patents into one head to get them to market.  So rather than putting technology into the head to make it better, the Oracle’s purpose was to bring as many patentable innovations to market.  Ultimately most of the concepts didn’t come to market on any other Gait heads, or if they did, they didn’t last long.

Brine’s first generation of helmets, the Triad ST and Triad XP were good helmets in theory, but had significant engineering/manufacturing issues.  While new and still in box the helmets would crack from the pressure applied by the screws used to hold them together.

I’d love to see this series continue… I could keep giving examples.