Not a cutting tool alone — with no blade it is inert; it seats the edge, it is not the edge.
Not close, fine, near-the-surface work — the long 5-1/4" body puts the hand back from the tip and gives up close control; a shorter handle is the right pick there.
Not a seat for wide mill blades — it takes 5/16" and 3/8" blades only; the 1/2"-and-wider flat-grind blades belong in the metal handles.
Not part of the riveted-knife wing — those trade knives carry their own fixed handles and are not extension tools.
Set the blade at the working length and secure it (mechanism per Hyde ⚑) before loading it — a long handle multiplies any wobble at the tip, so a firmly-set blade matters more here, not less. Use the flats to know the edge. Register a flat against the fingers so edge direction is felt, not seen. Handle to the hand, blade to the cut. The long body is for grip and leverage; pick it for force and reach, not for close detail. Don't lever the wood. A hardwood handle lasts for years unless it is used to pry on a seated blade — the long lever makes that abuse worse, so resist it.
Asked before buying
BUYER QUESTIONS, ANSWERED BEFORE YOU ORDER
What is this handle for?
Holding an extension (mill) blade at a cutting station. The blade wears out and gets replaced; the handle stays for years. Mount a 5/16" or 3/8" blade, set the extension, cut.
How long is it, and why does that matter?
5-1/4" — the longest of the four wood handles, for the fullest grip, most leverage, and reach. Shorter handles (4-1/2", 4-3/4") trade leverage for close control.
Which blades fit?
Any 5/16" or 3/8" mill blade — every extension blade in this line.
How does the blade lock in?
Not documented for the wood handles; the metal handles use set screws. We won't state the mechanism until Hyde confirms it.
Why does the store title drop "Flat Sided"?
A listing-title inconsistency; the catalog groups it under the flat-sided heading with the other three. It's the same class of handle.