How to judge is a good saliva collector?

Mainly four aspects:
1 ) stability–We added a saliva stabilizer to the saliva collector, and the formula is inconvenient to disclose. Stability test period, stable for one year, can be compared experimentally

2 ) that amount of DNA extract from the provided fix sample
3 ) that simplicity of the operation method for extract DNA. ( time cost is also cost ). These three aspects are related to reagents.
4 ) price ( cost performance ), despite the first three points about price is meaningless.

The excellent saliva collector should be perfectly combine with that subsequent DNA purification reagent, has good stability, large amount of DNA extracted by fix sample amount, simple and convenient operation for extracting DNA and high cost performance