Questions about knog. Oi small

Hi, can you confirm if the Knog Oi Classic and Knog Oi Small are supposed to be different sizes? I ordered all three with a Knog Oi Large and the first two seem to be exactly the same size. Is this normal?

The spring got overstretched and the plastic hammer got lost along the ride. Any pointers on how to order the plastic hammer part on the spring, please?

Does this "bell" also work in the rain? The conventional bicycle bell has a massive loss of sound when the bell body is wet; as a result, the biker is hardly perceived acoustically (and this with correspondingly longer braking distances). Thank you.