SN 1650lb Bombs

Does anyone know of any good reference material on the SN 1650lb bombs as used in WW1 from July 1918 onwards, and of any preserved examples? I know of the one in IWM London and RAFM Hendon. The one in RAFM Hendon is a Mk 2, I presume the main difference is the circular tail as opposed to the four fins on the IWM example. For those that don’t know what they look like, here’s photos of them both

I presume the amount of explosive inside differed, as although the official designation was 1650lb, the Observer on the first aircraft to drop one on the enemy describes it as a 1660lb’er