A patent thimble with a steel core covered inside by a silver liner and a silver cover on the outside ( actually three thimbles in one!) These were more expensive that all silver thimbles when they were sold as they couldn't be pierced by a needle and rendered useless.
The Dreema was Henry Griffith's answer to Charles Horner's Dorcas. There are a few others with different names Little Dorcas, Junior Dorcas, Doris etc.
This example has a band of stars and is stamped HG&S Dreema and 18 which is the size.
Finger aperture 15mm
Stock no. B21