You asking about the Silicone Squeeze Bottle ?
Don't think you'll find it separate to buy, if you had one you could size it with a pair of digital verniers, or just take the hit..
https://www.hcigar.com/prod_view.aspx?TypeId=69&Id=207&FId=t3:69:3
That's one approach, or you could just replace them with known good ones.
Mod maker had some squonk tubes for sale