Atlas HO Code 100 #4 Customline Mark V Turnout – Left – ATL391

Atlas HO Code 100 #4 Customline Mark V Turnout – Left – ATL391 is a modernized left-hand HO scale turnout featuring Atlas' newer 390 Series Mark V design. Built on the long-running Atlas Code 100 track system, this #4 turnout combines compact switching geometry with upgraded detailing, improved electrical features and compatibility with previous-generation Atlas Customline turnouts.

The Mark V design features a DCC-friendly configuration, blackened metal frog, rivetless switch points, cast-metal points and frog, separately molded guardrails and a dedicated frog contact lug. Atlas designed the 390 Series to remain fully compatible with the previous 280 Series Mark IV turnouts, allowing model railroaders to use ATL391 for new trackwork or as a drop-in upgrade for an older equivalent turnout.

What Is a #4 Turnout?

The #4 designation describes the turnout's frog geometry. Compared with broader #6 or #8 turnouts, a #4 turnout creates a more compact diverging route and requires less layout space.

This compact geometry makes #4 turnouts particularly useful for yards, industrial sidings, switching districts, storage tracks and other locations where fitting more track into limited space is important.

Because #4 geometry is tighter than higher-number turnouts, modelers operating long locomotives, passenger cars or other large equipment should consider the manufacturer's trackwork and minimum-radius recommendations when planning their layout.

Left-Hand Turnout

ATL391 is a left-hand turnout. When approaching from the single-track or point end, the straight route continues ahead while the diverging route branches toward the left.

This makes the turnout useful anywhere a siding, yard track, industrial spur or secondary route needs to branch toward the left from the primary route.

New Atlas Mark V Turnout Design

The Atlas 390 Series Mark V turnouts update the company's established HO Code 100 Customline turnout system with improved appearance and electrical features while maintaining compatibility with previous trackwork.

• DCC-friendly turnout design
• Blackened metal frog
• Rivetless switch points for improved appearance and electrical conductivity
• Cast-metal switch points and frog
• Separately molded guardrails for improved realism
• Dark-colored guardrails and scale-size throwbar
• More realistic scale-size spike head detailing
• Frog contact lug for easier powered-frog wiring

Powerable Metal Frog

The Mark V turnout incorporates a metal frog that can be powered when desired. Atlas added a dedicated frog contact lug to make connecting power to the frog easier than on previous designs.

Powering the frog can help provide continuous electrical pickup through the turnout, particularly for locomotives with short wheelbases or limited electrical pickup. The appropriate wiring arrangement will depend on the layout's electrical and turnout-control system.

Compatible with Atlas Mark IV Turnouts

One of the most useful features of the 390 Series is backward compatibility. Atlas designed these Mark V turnouts to be 100% compatible with the corresponding 280 Series Mark IV turnouts.

This allows existing Atlas Code 100 layouts to be upgraded without redesigning the surrounding track geometry. Modelers replacing an older equivalent Mark IV turnout can use the newer Mark V version as a drop-in replacement while gaining the updated detailing and electrical features.

Atlas HO Code 100 #4 Mark V Left Turnout Features

• HO Scale model railroad turnout
• #4 turnout geometry
• Left-hand configuration
• Atlas Customline Mark V design
• 390 Series turnout
• DCC-friendly construction
• Blackened metal frog
• Metal frog can be powered when desired
• Dedicated frog contact lug
• Rivetless switch points
• Cast-metal points and frog
• Separately molded guardrails
• Scale-size spike head detailing
• Dark-colored scale-size throwbar
• Compatible with corresponding Atlas 280 Series Mark IV turnout geometry
• Code 100 nickel silver rail
• Black injection-molded plastic ties
• Designed for Atlas HO Code 100 track systems
• Atlas manufacturer item number 0391
• Fusion Scale Hobbies SKU ATL391

Ideal for Yards, Sidings & Industrial Track

The relatively compact #4 geometry makes ATL391 especially useful for areas where space efficiency is important. Yard ladders, industrial switching areas, locomotive facilities, storage tracks and compact sidings can all benefit from the shorter geometry of a #4 turnout.

For visible mainlines or routes regularly handling longer equipment, a broader turnout such as a #6 or #8 may be preferable where sufficient space is available.

Manual or Powered Turnout Operation

Atlas specifies that the Mark V turnout can be operated with compatible Atlas under-table, standard remote or standard manual switch machines, giving model railroaders several options for controlling the turnout points.

Browse our Atlas HO Switch Machines collection for turnout-control components for Atlas HO trackwork.

Build with Atlas HO Code 100 Turnouts

Browse our complete Atlas HO Code 100 Turnouts & Switches collection for additional turnout sizes and configurations for yards, sidings, industrial tracks and mainlines.

Combine this turnout with products from our Atlas HO Code 100 Track collection to build or expand a complete HO scale track system.

Complete Your Trackwork

Use Atlas HO Code 100 Flex Track for custom track alignment around yards and industrial areas, or combine the turnout with Atlas HO Code 100 Straight Track and Atlas HO Code 100 Curved Track.

For rail joiners, terminal connections, track nails and other installation components, browse Atlas HO Track Accessories.

Atlas Code 100 track can also be installed over Atlas HO Cork Roadbed to create a raised track profile and foundation for ballast and finished scenery.

Shop HO Scale Model Railroad Track

Explore our complete Atlas HO Scale Track selection or browse Model Railroad Track for additional track systems, turnouts and layout-building components.

Shop additional products from Atlas Model Railroad and browse Atlas In-Stock Products.