Species in this pack include
Swan mussel ( Anodonta cygnea)
Pea mussel ( sphaerium corneum)
Trapdoor snail ( viviparus viviparus)
Faucet snail ( bithynia tenticulata )
This pack comes in 3 options 
  Small  - 1 swan mussel 
                   5 pea mussels 
                   5 Trapdoor snails
                   20 faucet snails
Medium - 5 swan mussels
                    20 pea mussels 
                    20 Trapdoor snails
                    100 faucet snails
    Large - 10 swan mussels
                    50 pea mussels
                    50 Trapdoor snail
                   250 faucet snails
Each species filters Small organic particles and algae from the water colum and can help control green or murky water, both snail species like other pond snails will also eat waste and detritus from the bottom aswell as scrape algae from rocks and plants.