Are all of HUAWEI Smartwatches compatible with iOS and Android phones?

Yes, all HUAWEI smartwatches are compatible with iOS and Android phones.

In which sizes is the HUAWEI WATCH GT 3 available?

The HUAWEI WATCH GT 3 is available in 42mm and 46mm.

Which materials are used on the HUAWEI WATCH GT 3 straps?

The HUAWEI WATCH GT 3 straps are made out of Metal(Stainless steel), Plastic(nylon+glass fiber) and Leather.

Is the HUAWEI WATCH GT 3 water resistant?

Both versions of the HUAWEI WATCH GT 3 are water resistant up to 5ATM. Note: Syntax leather strap is not water-resistant.Water resistance is only given while using it for shallow water activities like swimming in a pool or ocean. Hot showers, saunas, water skiing or other high-pressure watersports may not be suitable.