My first gravity was the msr system. With it I thought back flushing was tipping my nalgien over and running some of my hard earned filtered water back through which rarely did much. I tried several filters and stumbled on the sawyer. I feel I have the best of all world's now. Dirty bag with pre filter. Good filter and the msr deal that connects to nalgien bottles and about anything else. I do not miss pumping. And the syringe works very well for back flushing.