Time glass

Time Glasses were objects resembling oversized magnifying glasses. They allowed users to look into a time stream moving at a different rate from their own. This was particularly useful in kindness facilities treating terminal patients, as the sick could experience their entire lives in a compressed time stream, while only a single day passed in absolute time. A Time Glass could sync up the two time streams, allowing patients and their loved ones to communicate with each other.

Time Glasses were available at the Two Streams Facility for use by Apalapucians who had contracted the deadly Chen-7 plague and their families. (DW: The Girl Who Waited)

The Doctor had one in his drawing room. (VG: The Gunpowder Plot)