As long as Dangle supports this product, their product can be passed down through countless generations, making this a prime example of a well-engineered sustainable solution to a modern problem. The rubber stopper cleverly houses the bowl piece and retains it to silence any metallic rattle due to vibration during transport. The stopper also serves to retain any residual moisture after dirtied bong water has been removed before storage and perhaps precludes contamination from dust or debris while dangling from a bag (I recommend discrete storage in a Pelican Ruck R40 or Safe Locker 420.) I have used both, and both store the bong well with other accouterments (i.e., Bic Lighter, Flower Scooper, BITOMIC 50mL Herb Container, and Santa Cruz Shredder 3 Piece Medium grinder.) I do not recommend packing bowls over the stopper, as built-up resins may deposit and prove difficult to remove without the use of solvents. However, regular cleaning between uses (Dawn dish soap or similar and warm water,) packing over a grinder instead, and monthly ultrasonic cleanings (room temperature solution; 1:10 diluted Simple Green) negates this issue. After all, the compact form of this device fits into many consumer-grade and affordable ultrasonic sinks. Take caution, however, and never clean any of these pieces with waters previously used for cleaning leaded mechanical components, as inadvertent consumption of heavy metals may occur.