From booklet:

Bikini instructions are for size Small. Changes for Medium are in parentheses.

MATERIALS - Sport Yarn Weight

SPINNERIN Sabrina (50-g) Bikini: 2(3) White (MC). Umbrella: 6 MC. Both: 1 ball each of Brown, Orange, Blue, Yellow, Green, Rose, and Rust

1 Golf Umbrella: .25 inch elastic ribbon

CROCHET HOOK: “Boye or Diana” Size F OR SIZE TO GIVE GAUGE

CROCHET HOOK: “Boye or Diana” Size G

GAUGE F HOOK: 3 mesh = 2 inches
2 rows = 1 inch

FINISHED MEASUREMENTS (in inches)
Hips: 33(36)
Bra: Small(Medium)