For 18 months mine was going out through the open door and back in the same way i add a sputnik and i still let them out through the door but they come back in through the sputnik with now the ets in it , they all was going through it withbin max two weeks ,i got the xl tauris system and it fits straight into the standard economy sputnik from bjf food wales near kiverton pal u can come over to worksop anytime if you want a look 1st hope this is help too u