The Micro Engineering 26-109 is a pack of 6 G scale set-screw rail joiners for Code 332 rail — heavy-duty mechanical joiners with a screw that bites the rail web, designed for outdoor garden-railway use where rail expansion/contraction from sun and weather will eventually pop a slip-on joiner loose.Use: The set screws grip both rail webs at the joint, holding rail-to-rail even as the rails creep with temperature. Standard slip-on joiners are fine indoors; set-screw is the right choice for any track that lives outside year-round.About Micro Engineering: Micro Engineering is the gold standard for prototypical fine-scale track among serious modellers — known for scale-size moulded ties / tie plates / spike heads, irregular tie spacing that matches real-railroad practice, and fine-scale code-correct rail. Scale: G (Large Scale, 1:22.5 / 1:24) Code: Code 332 Hold: Set-screw (mechanical clamp on rail web) Pack: 6 pieces Distributor SKU: 255-26109 In stock at Oakville Model Trains Depot.