You have a toolbox gap to fill, and two very different kits are on the table. One is a comprehensive assortment of Grade 8 hex cap flange frame bolts and locking flange nuts. The other is a set of small stainless steel compression springs. They are not competing for the same job, so the right choice comes down to the kind of repair you do most often.
Quick verdict
If you assemble frames, flanges, or heavy brackets, the hex cap flange bolt and nut kit gives you a wide spread of inch-size bolts with matched locking nuts. If you work on small mechanisms, springs, or DIY repairs, the compression spring assortment is a practical starter kit.
At a glance
| Feature | Hex Cap Flange Bolt & Nut Kit | Compression Spring Assortment |
|---|---|---|
| Price | $139.99 | $10.90 |
| Fastener type | Bolts and locking flange nuts | Compression springs |
| Finish / material | Zinc yellow trivalent on steel | Plain finish on 304 stainless steel |
| Included sizes | 1/4-20, 5/16-18, 3/8-16, and 1/2-13 with matching flange locknuts | Wire 0.3-0.8mm, outer diameter 2-8mm, free length 5-30mm |
| Storage | Compartment box | Compartmentalized case |
Where each kit wins
The bolt kit wins when you need Grade 8 rated hardware and a matched set of nuts. The spring kit wins when you want a broad range of small, corrosion-resistant springs in a compact, organized case. For a shop that regularly does structural bolting, the Grade 8 kit is ready to go. For a general DIY drawer, the spring assortment fills a niche that bolts never will.
Grade 8 Hex Cap Flange Frame Bolt Zinc Yellow & Locking Flange Nuts Kit - 447 Pc
This 447-piece kit is built around flange head bolts in four inch sizes: 1/4-20, 5/16-18, 3/8-16, and 1/2-13. It includes 100 1/4-inch locking flange nuts, 50 5/16-inch, 40 3/8-inch, and 15 1/2-inch nuts. The zinc yellow trivalent finish on steel adds corrosion resistance, and the compartment box keeps sizes separated. The limitation is that the assortment covers only these four thread sizes, so bolts outside that range won't be in the box. If your projects stay within these sizes, this kit gives you enough hardware to handle a range of frame and flange assembly jobs without running to the store.
390 Piece Compression Spring Assortment Kit 28 Sizes Small Steel Springs Set
The 390-piece assortment covers 28 compression spring sizes, with wire diameters from 0.3mm to 0.8mm, outer diameters from 2mm to 8mm, and free lengths from 5mm to 30mm. The 304 stainless steel with a plain finish is the main draw, since it stands up to damp conditions better than plain steel. The labeled compartment case makes finding the right spring quick. The catch is scale: these are small springs meant for light loads, so they won't substitute for bolts or heavy-duty structural parts. Slight magnetism from the manufacturing process is possible but shouldn't affect normal use.
Final choice by use case
Choose the hex cap flange bolt and nut kit when you need structural-grade bolts and nuts in inch sizes, especially for frame or flange assembly. Choose the compression spring assortment when you need small stainless springs for DIY projects, household fixes, automotive trim work, or hobby mechanisms.
