Lever Operated Dome Style Lavatory Drain Deluxe for sinks Not requiring an overflow by Mountain, Mountain MT1001/CPB, Mountain MT1001/BRN, Lever-Operated Dome-Style lavatory drain for sinks not requiring an overflow. Decorative drains for vessels, glass sinks and lav sinks, Mountain plumbing MT1001. 4 1/4" Tailpiece. 1 1/4" O.D. No threads. Drain opening 1 1/2". Top piece on top of tailpiece is 3 5/8" tall, making the total length 7 7/8".