This workout requires knowledge of the 4 main strokes of swimming, Butterfly, Backstroke, Breaststroke, Freestyle. You can substitute the IM work for a stroke you are comfortable with like Freestyle. You will also need access to a pair of fins. Again if you can't access fins, try the kick without.
4*25 as 12.5 max as 12.5 easy
8*50 as 25 sculling + 25 drills
9*50 butterfly kick on the back with fins
6*50 cool down