These are great for resistance training and if used correctly can improve your paddling indurance.
If you get one, get it from Lee at Fit2Surf.com
. He has contributed some surfing fitness articles
to this site, and sent a cord for review
. He's also the author of Complete Guide to Surf Fitness
, and has worked with top surf athletes Ben Skinner and Oli Adams, and developed fitness coaching with the U18 British surf team.