Either one of these 
https://lolibrary.org/items/btssb-blouse-with-detachable-collar-and-sleeves
https://lolibrary.org/items/btssb-blouse-with-removable-collar-and-sleeves

White colour. Perfect condition. Super rare and unique piece, crocheted lace + berry motif lace on collar. Truly old school essential ✨️ Sleeves on the last pic are default sleeves for this blouse but they're way too short for me so I replaced them with sleeves from another Baby blouse. Selling both of pairs lol. 
Manual flat measurements: 
Length 46cm, shoulder width 36cm, bust 39cm, sleeve length with default set 53cm, with 2nd set 57cm. 

This item will be shipped from Czech Republic, please send me a message to get a shipping quote.