Bit of a language barrier here. I think the OP means "safety" when referring to insurance. Carlos, this site might a little difficult to understand as it's in english but there are many good pics of the 1900 Colts there with the sight safety:
This safety device was on the early 1900s but was deleted and usually you find that they have been removed by the factory. Original 1900s with the sight safety still intact are pretty rare.
Perhaps one of our members speaks spanish and maybe can help you understand a little better.
This is from Sam's site above: Sight Safety - locked in upward position, this functions as the rear sight. The sight safety and hammer were color case hardened.
Translated to Spanish (from an online translation engine):
Seguridad de vista - bloqueado en posición hacia arriba, esto funciona como el alza. La seguridad de vista y el martillo fueron endurecida de caso de color.