Hybrid Raceboards are defined as any ISAF Approved Production Raceboard that is 310 cm, or less, in length.
The boards currently classified as hybrid include:
Bic Techno 293
Bic Sport Hybrid
Exocet Pacer and Pacer Pro
Neil Pryde RS:X
Neil Pryde RS:One
Starboard Phantom 295 AST
Surfers Group Hybrid Race One
For full details of these boards and to see the full production boards list: http://www.sailing.org/11675.php
Note - there are older models registered with ISAF that may also be raced in the R310 division.