Based on this product's specifications, here are some alternatives and similar models
Koelner D-TU-121 Bolt-Down Post Support 121 mm
Summary description:
The Koelner D-TU-121 is a high-quality bolt-down post support designed for stable and secure mounting of wooden posts to concrete surfaces. With a 121 mm diameter, this steel support provides excellent structural integrity for fences, pergolas, and garden structures. Its durable construction ensures long-lasting performance and resistance to environmental factors, making it an essential component for professional construction and DIY landscaping projects.