Co-Motion Co-Pilot tandem bicycle. Vintage: Mid -to- late 1990s. Approximately 15,000 miles. 
The Co-Pilot model has S&S couplers in the frame that allow the frame to break down into 3 pieces and package into a 26" x 26" x10" soft-sided case that can be checked on to most airlines with no oversized charge. The soft-sided case is included along with all of the internal packaging and the special spanner wrench to work the couplers. 
 
The frame is chrome-moly steel. 
 
Specs:

Weight = 40 pounds (approximately). 
Wheelbase = 68". Crank center to top of top tube = 20" (Captain), 17" (Stoker). Captain seat tube to head tube = 21". Seat tube - seat tube = 27". Crank - crank = 27.5". Head tube = 5". 
 
Chainrings = 54t/44t/32t. Cassette = 32t - 11t. Drivetrain is 3x8. 
 
Rear wheel = 40 spoke. Front wheel = 36 spoke. 
 
Derailleurs = Shimano Ultegra (F&R). Shifters are Shimano Ultegra bar-end shifters. 
 
Brake levers = DiaCompe 287V. Brakes = Avid direct pull "V" rim brakes. 
 
Headset = Chris King. Hubs = Phil Wood. Rear hub is threaded to accept an Arai drum brake (not included). Cranks - Ritchey Logic. 
 
Includes 2 pairs of pedals, 4x stainless steel water bottle holders, rear rack, panniers, rear trunk, frame mounted tire pump, removeable fenders. $150 shipping is within continental US. 
 
This bike has been lovingly ridden and maintained for approximately 15,000 miles. It has always been stored indoors. Never crashed. Never dropped. Seldom ridden in the rain or wet conditions. We have ridden it over nearly every mountain pass in Colorado. Ridden to the top of Mt. Blue Sky (>14,000'). Ridden on the Icefield Parkway in Alberta, Canada and ridden to the top of Mt. Haleakala on Maui.