There are two models, Part Nos. 1224844 and 1224846. The 1224844 is for Al-Ko chassis marked 'M' (model year 2010) with all necessary provisions for for its installation and the 1224846 for older Al-Ko chassis and other makes. The former will cost 2299_ (including 19% German VAT) and weighs 29kg and the latter 2399_ and weighing 36kg (because it requires an additional chassis crossmember). This crossmember reduces ground clearance by 5cm, the other model without has no effect on ground clearance.
What is surprising is that both models are rated for caravans with an MTPLM of up to 2250kg. This suggests to me that it is a bit over-engineered for the majority of caravans, hence probably the hefty price.