Based on this product's specifications, here are some alternatives and similar models
Foam Frame for Waterbed 180 x 200 cm Shumee (model 4855)
Summary description:
Foam frame designed for a 180 x 200 cm waterbed by Shumee, model 4855. Provides structural support and edge stability using high-density foam to hold the water mattress in place. Suitable for assembling or repairing a waterbed base, it improves mattress positioning and user safety while maintaining mattress flexibility.