I'm not sure 100% but it look like some part of safety belt is missing. Its compleat for one child but I don't know how to do with 2. Additional wheels one plastic, one normal and adaptors are included. The item "WeeRide Deluxe Bike Bicycle Trailer Green/Black Jogger Stroller Kids Carrier" is in sale since Friday, December 29, 2017.
This item is in the category "Sporting Goods\Cycling\Bike Accessories\Trailers". The seller is "mark_bargain_bits" and is located in Burntwood. This item can be shipped to United Kingdom.