Bolt-down post bases are commonly made for square timber posts of 70×70 mm, 90×90 mm and 100×100 mm, and some models take rectangular or larger sections. The cradle or U-profile holds a defined post width, and adjustable versions with side bolts cover a small range, so measure the real post and match it to the base's internal opening rather than the nominal size.

Fix a bolt-down post base by marking the bolt holes, drilling into cured concrete with a masonry bit, and securing the base with expansion or resin anchor bolts. Keep the base at least a bolt's-length in from any slab edge to avoid cracking, check it is level, then tighten evenly before fitting the post with the recommended screws. Allow new concrete to fully cure before drilling.

Bolt-down post bases are typically hot-dip or electro-galvanised steel, giving a zinc coating that resists corrosion outdoors on concrete and paving. The galvanised finish suits fences, decks, pergolas and handrails exposed to rain; for coastal or de-icing-salt areas, choose hot-dip galvanised or stainless anchors and a base with a raised standoff so the post foot drains and stays dry.

Whether anchor bolts are supplied depends on the model, so check each product's specification before ordering. GeZu Impex states the included fixings and the recommended anchor size and post-screw pattern for each bolt-down base. Where bolts are not supplied, choose expansion or resin anchors rated for concrete and matched to the base's hole diameter, and pick a heavier-gauge base for taller fence, deck or pergola posts that carry more load.