[Pastor]

I think hf stands for something silly like hard fin and ld for light duty. Either way the hf's are much stiffer than the ld's and are better suited to up and down type diving whereas the ld's are softer and are ideal if you do a lot of surface swimming. I use hf's for recreational freediving in the Red Sea and they are awesome but I use Omer Millenniums for hunting with at home.