Hello and welcome to the fora, kamilica.
Presumably the windowed ones are also ceramic with a quartz glass window. This is expensive to manufacture (buy) especially when most devices will only ever be programmed once. Because of this they come up with "OTP" One Time Programmable devices which are the same inside but just molded in plastic. If you need to re-programme these, you throw it away and use a new one.
This is probably what you have. If you don't want what is programmed into them now they are worthless.
