Kwikset 665 Double Cylinder Deadbolt with SmartKey: The Contractor's Security Swiss Army Knife

The Kwikset 665 combines adjustable latch technology (2-3/8” or 2-3/4” backset) with SmartKey re-keying and double cylinder operation — three features that solve real contractor headaches in one deadbolt. For Montana contractors dealing with mixed door stock, rental property turnover, and glass-panel security vulnerabilities, this deadbolt hits the sweet spot between versatility and value.

At 4.3 to 4.4 stars across reviews, contractors appreciate what matters: installation flexibility and the ability to re-key without removing the lock. The double cylinder design addresses a specific Montana problem — ranch entries with decorative glass panels that wildlife (or intruders) can break through.

Technical Specifications That Actually Matter

The adjustable latch switches between 2-3/8” and 2-3/4” backsets — crucial when retrofitting older Montana homes where door prep varies from room to room. The round-corner faceplate measures 1” x 2-1/4”, fitting standard residential preps without modification.

Specification	Value	Source
Cross Bore	2-1/8 inches	Manufacturer
Edge Bore	1 inch	Manufacturer
Door Thickness	1-3/8” to 1-3/4” standard (up to 2-1/4” with thick-door pack)	Manufacturer
Throwbolt	Full 1-inch solid-core	Manufacturer
Security Grade	ANSI/BHMA Grade 3 (Residential)	Manufacturer
Exterior Diameter	2-1/2 inches	Manufacturer
Projection	1-1/8 inches (both sides)	Manufacturer

Installation rates easy to moderate with full reversibility for right or left-handed doors. No drilling new holes on standard preps. The 1-inch throwbolt provides real engagement into the strike plate — not the 5/8” joke bolts found on builder-grade locks.

SmartKey Technology: More Than Marketing Fluff

SmartKey allows re-keying in seconds using any KW1 keyway key through a simple 3-step process. This isn’t pin tumbler manipulation — it’s a patented side-locking bar system with stainless steel racks and pins that replaces traditional pin-and-tumbler design.

For property managers juggling multiple rentals across the Flathead Valley, SmartKey eliminates locksmith calls between tenants. Keep one key blank in the truck, re-key on site. The BumpGuard technology resists lock bumping — a real concern in vacation rental markets where keys float around.

The system works. Period. No removing the lock, no pin kits, no tiny springs launching across the job site. Compatible with any Kwikset KW1 key, so standardization across properties stays simple.

Double Cylinder Applications in Montana

The 665 requires a key on both exterior and interior sides, making it ideal for doors with glass panels or windows within 3 feet. This addresses a specific vulnerability in Montana homes — decorative entry doors with glass inserts that bears, elk, or humans can break to reach the thumb turn.

The double cylinder design brings a safety consideration: it requires a key for emergency exit from the interior. Montana contractors know to specify these for entries with nearby glass but never for primary egress routes. Workshop entries, detached garages, and secondary ranch entries make perfect applications.

ADA compliance doesn’t apply to double cylinder locks since they require two hands and a key to operate. Keep these out of commercial projects and primary residential exits.

The Bottom Line for Montana Contractors

The 665 earns its place in the contractor toolkit through adjustable latch versatility and SmartKey convenience. Kwikset markets this as part of their 600 series — “the largest-selling deadbolt in America” — with double cylinder operation on both sides.

Grade 3 security won’t stop a determined thief with a sledgehammer. But combined with proper door reinforcement and strike plate upgrades, it handles 90% of residential security needs. For higher security requirements, Kwikset’s 785 or 994 series offer Grade 2 ratings.

The real value sits in the combination: adjustable latch for mixed door preps, SmartKey for property management efficiency, and double cylinder design for glass-vulnerable entries. At contractor pricing, it solves multiple problems without breaking the budget. Covered by Kwikset’s lifetime mechanical and finish warranty for the original purchaser, though smart contractors know the SmartKey mechanism takes more abuse than traditional cylinders.

Frequently Asked Questions

How difficult is the SmartKey re-keying process?

The SmartKey system re-keys in seconds using any KW1 keyway key through a simple 3-step process. Insert current key, turn quarter-turn, insert SmartKey tool, remove tool, remove current key, insert new key. Done. No pins, no special skills.

Can I install this on doors thicker than 1-3/4 inches?

Yes, with the optional thick-door pack, the 665 accommodates doors up to 2-1/4 inches thick. This covers most residential applications including insulated steel doors.

What’s the real difference between Grade 3 and higher security grades?

ANSI/BHMA Grade 3 certification indicates residential use standards. Grade 3 handles forced entry attempts typical of residential break-ins. Grade 2 adds cycle testing, stronger materials, and higher impact resistance for commercial traffic.

Should I worry about the adjustable latch being hard to set?

Customer reviews mention occasional difficulty setting the latch to 2-3/4 inches. The adjustment mechanism works but sometimes requires patience. Set the backset before installation while you have better access.

When should I avoid using a double cylinder deadbolt?

Never use double cylinders on primary egress routes or where emergency exit is critical — they require a key to exit from inside. Perfect for entries with nearby glass, workshops, and secondary doors. Not for main exits, bedrooms, or anywhere fast evacuation matters.