Simplicity 5754 vintage sewing pattern, dated 1964.

Misses' Duster or Pajamas with Detachable Collar:

Duster Views 1,2 have high round neckline, front button closing, gathered set-in sleeves; front and back gather to fit yoke. Elastic casing at lower edge of sleeve forms self ruffle. Pajama top V 3 like duster, but shorter; pants have elastic casing at waistline. Views 1 and 3 features detachable tie collar and long sleeves. View 2 has short sleeves.

Size  16:

Bust  36 inches / 92 cm

Waist 28 inches / 71 cm

Hip    38 inches / 97 cm

Pattern is PRINTED, UNCUT and factory folded. Envelope has paper tanning and light spotting, some small tears at opening.

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https://allthepreciousthings.com/collections/sleepwear