These are older models which have been used. I've tested the impellor units briefly and they work but I can't guarantee performance. The aquarium capacity for which these are suitable are guidelines only and would depend on how the aquarium is stocked and possibly other factors. In the photos the more rounded units are the 'plus' models and the 'square' are the pre-plus models. I have an electronic copy of instructions for the plus models but not for the pre-plus models.
Fluval 1 Mod1 (approx. max. capacity 30 litres)
Fluval 2 (info label has code L-02002; approx. max. capacity 60 litres)
Fluval 2 plus filter section only (impellor unit scrapped due to damaged cable; approx. max. capacity 60 litres)
Fluval 3 filter section only (impellor unit scrapped due to damaged cable - info label had code L-02002; approx. max. capacity 120 litres)
Fluval 3 plus (info label has code L-35033 07/08; approx. max. capacity 120 litres)

Fluval Aquarium Filters (Sharmans Cross B91)