The Auto-Siphon. A $15 contraption built by Fermtech Ltd., probably one of the most valuable tools in any well-equipped homebrew's brewing toolbox. It comes in two sizes, 3/8" and 1/2" diameter. Originally I opted for the 3/8" and later moved up to the 1/2" diameter one, naturally because larger diameter equals higher volume flow. I sang its praises at every siphon-discussion turn until...until it betrayed me.
The Achilles' Heel of the Auto-Siphon is the seal at the bottom of the inner tube that contacts the outer tube. When this seal wears or is otherwise defective, it will let air into the siphon. Perhaps not enough air to completely break the suction seal, but enough to create a long, steady line of very large bubbles that'll give you nightmares of your frail and delicate Bohemian Pils tasting like a mouthfull of wet cardboard.
(In case you're confused on that last line, do some reading up on oxidation.)
My second Auto-Siphon died an early death at the hands of a defective seal, summarily and unceremoniously tossed into the trash can. Order up #3, drop another $15.
Straight from the package and into the sanitizer it goes, dunked into the beer, start the siphon and what appears before my disheartened eyes but a long, steady stream of bubbles coming from down at the seal. Another $15 down the drain.
I'm not the kind to let the same dog bite me 3 times (who would've expected twice?!?!) so I'm done with the Auto-Siphon, despite claims on the Fermtech website of a new and improved seal that "prevents introduction of air at the seal." Luckily, I can still use the inner racking cane and tubing to siphon. Just need to come up with a Plan B to get beer into the keg without oxidizing the bejesus out of it along the way.