Address: Sergelgatan 17
Telephone: 08 21 1944
Hemtex sells anything textile: bed linens (also duvets and pillows), curtains (including shower curtains), towels, bath robes, table cloths, and so forth.
There are several Hemtex branches throughout the city, but this one on Sergelgatan is the largest, and in my opinion the display is also the best among all the branches (so you are tempted to buy many things here).
And, as the shop name suggests, there are more. This store even sells stationery and some glassware including Iittala.