Photo Cube Pocket Watch Fob

This is a double-albert pocket watch chain with a rotating photo cube (4 photos with beveled glass, silver sides).
The photo cube measures 14.7mm x 10.5mm. The photos are 10.7mm x 10.1mm.
The photo #1 above is:
Wilhelm I; Kaiser Wilhelm I; full name Wilhelm Friederick Ludwig, born March 22, 1797, died March 9, 1888.
He was the King of Prussia from January 2, 1861 to March 9, 1888.
He was the first German Emperor from January 18, 1871 to March 9, 1888.

The photo #2 above is:
Frederick III, born October 18, 1831, died June 15, 1888. Son of Wilhelm I.
Kaiser Frederick III, German Emperor; King of Prussia March 9 - June 15, 1888. He had been Crown Prince for 27 years before his short reign as King of Prussia which was cut short from unsuccessful treatments for cancer of the larynx.

The photo #3 above is:
Wilhelm II, Freiderk Wilhelm Viktor Albrecht, son of Frederick III, born January 27, 1859, died June 4, 1941.
He was the last German Emperor (Kaiser) and King of Prussia, ruling the German Empire and the Kingdom Of Prussia from June 15, 1888 to November 9, 1918. He was the grandson of the British Queen Victoria.

The photo #4 above possibly is:
Tsarevich Alexei Nicolaevich, son of Nicholas II, Emperor and Autocrat of All the Russias from November 1, 1894 - March 15, 1917.

The double-albert pocket watch chain is silver marked (lion facing left), on all the chain links, clasps & T-bar.
London Date Letter D dating 1799
Makers mark of: H B & S; Herbert Bushell & Sons

Thanks for looking,
Dave