Here we have the perfect upstand clamp for use with your new motorhome shelf. These are only suitable if you want the shelf sitting just above your upstand like the picture. If you need them higher because of upholstery then they are not suitable.
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There are Stainless steel adjustable clamps that can be used on your kitchenette upstand to suit thicknesses from 4mm through to 40mm.
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This is for a PAIR of brackets.