Product Description
3.5" × 3.5" White Post Adapter — Fits SLO74W / SLO78W Caps
- Size-down solution — Reduces a 4" cap base to fit actual 3.5" × 3.5" wood posts.
- Cap compatibility — Designed for Classy Caps SLO74W and SLO78W models (Original & Regal).
- Clean install — Snaps/sets inside the cap base for a snug, rattle-free fit.
- Durable PVC — UV-stable white material for long outdoor service.
- Fast retrofit — Ideal when mixing vinyl caps with wood posts across a project.
This 3.5" × 3.5" adapter makes it easy to use popular 4" Classy Caps models on standard wood 4×4 posts. It installs inside the cap base to reduce the opening, centering the cap and tightening the fit so the finished result looks purpose-built rather than adapted. Keep several on hand when your job blends vinyl and wood sections — it streamlines ordering and avoids hunting for separate 3.5"-specific caps. For projects that also include 6" feature posts, pair the adapted caps with the aluminum Cambridge 6" × 6" Solar Cap on larger columns to keep the styling consistent. If you’re standardizing on an aluminum cap for 4" square posts elsewhere, consider the Imperial Aluminum Solar Cap as a durable companion piece.
Specifications
| Function | Reduces 4" cap opening to fit 3.5" × 3.5" wood posts |
| Compatible Caps | SLO74W (Original 4×4 PVC) and SLO78W (Regal 4×4 PVC) |
| Material | White PVC (UV-stable) |
| Install | Fits inside cap base; tool-light installation |
Installation (Quick Steps)
- Prep — Confirm your cap model (SLO74W/SLO78W) and actual post size (3.5").
- Insert — Seat the adapter inside the cap base per instructions.
- Mount — Fasten cap/adapter assembly to the wood post.
- Check — Verify snug fit and cap alignment.
Buying Guide
- Inventory win — Use one 4" cap SKU across vinyl and wood by adding this adapter on wood runs.
- Finish match — White PVC blends with common fence/rail systems.
- Not universal — This model is specifically for SLO74W/SLO78W; verify part compatibility before ordering.
Frequently Asked Questions
- Will this work with other 4" caps?
- It’s designed for SLO74W/SLO78W. Check your cap’s documentation for adapter options.
- Does it change the cap height?
- No — it nests inside the base; overall appearance remains the same.
- Is it paintable?
- It’s white PVC; many users leave it as-is to match white caps and railing.
Comparison
- 3.5" Adapter (this product) — Reduces 4" cap opening for 3.5" wood posts; SLO74W/SLO78W specific.
- 5" Adapter (companion) — Upsizes certain 4" caps to 5" vinyl posts (cap-dependent).
- No adapter — Use caps natively sized to your posts when a dedicated model exists.
