Workout

Warm Up (600)
Swim 12 x 50's on :50

Set (600)
2 rounds
100 back on 2:00
4 x 50 kick on 1:00

Set (1800)
3 rounds
2 x 150 on 2:15
...100 free/50 non free 
4 x 50 free build on :50 
100 FAST choice 

Set (300)
6 x 50's drill on :50
...catchup stroke

Cool-down (200)
200 EZ choice