engineer Werner Stengel and with designers and management of client theme parks. Lift hills Early Bolliger & Mabillard coasters feature an element known as a "pre-drop", a short drop after the top of the lift hill and before the start of the first drop, designed to reduce stress on the lift chain. The flat section between the pre-drop and the first drop serves as a shelf to support the weight of the train, reducing related stresses on the chain. On most coasters without a pre-drop, the weight of the train tends to pull on the lift chain as it begins its descent because the latter half of the train is still being lifted by the chain. Pre-drops have not been used on the company's Dive or Flying coasters, or on hyper coasters built after 1999. OzIris at Parc Astérix was the first B&M inverted roller coaster that does not feature a pre-drop. Ever since, no coaster built by B&M has featured a pre-drop because the chain accelerates to acquire the same speed as the train when it is being taken over by gravity after it passes the crest . Trains Most of Bolliger & Mabillard's roller coaster trains use four-abreast seating. Each car has one row of four seats, while the train length can vary between coasters. All of the company's coaster models, except the Dive Coaster and Wing Coaster use this configuration. The Dive Coaster uses six, seven, eight or ten-abreast seating, with two or three rows of seats. For example, Griffon at Busch Gardens Williamsburg, uses ten seats in three rows, while Krake at Heide Park uses six-across seating in three rows. On recent hyper coaster projects, B&M has used a new car design that has two rows of two seats; the two seats in the rear of the car pushed out from the centerline so that the four seats resemble a V formation. This formation has only been used on Behemoth at Canada's Wonderland, Diamondback at Kings Island, Intimidator and Shambhala: Expedición al Himalaya at PortAventura Park, in the resort PortAventura World. In 2013, B&M introduced a new car design that has two rows of two seats, however, they are not in a V formation. All B&M hyper coasters use a type of restraint called a "T-bar" or "Clamshell" restraint, which consists of bar with a cushioned lap bar with two handles for riders to hold on