Amazon.com again offers the PermaFLOW Never Clog Drain, model no. PF-07001, for $19.99. Pad your order over $25 to avoid about $5 in shipping. That's 50% off and tied with our October mention for the lowest total price we've seen for such a drain. The PermaFLOW drain features a dial that can be turned to rotate an internal wiper to remove any build-up.