Grease nipples have a thread for screwing in or a spigot for pressing in. They are mainly used in machine and vehicle construction and on agricultural and construction machines. Here they ensure that drive shafts, axles, bearings and threads are lubricated regulary.
 
Specific Details
Dimensions: 15mm x 12mm likely indicates a 15mm length and 12mm hex/spigot width, typical for a compact, straight or 45° grease nipple used in automotive or small machinery bearings.
Weight: 600g for 100 pieces (~6g per nipple) suggests lightweight zinc-plated steel or brass construction, ideal for standard applications.
Quantity (“67 cs”): Likely 67 pieces, possibly a subset of the 100-piece box. If “cs” refers to something else (e.g., a catalog code or unit), please clarify.
“S.K.”: Likely a brand (e.g., S.K. Tools, known for automotive/industrial tools) or a specific model. Without explicit confirmation, I’ll treat it as a standard grease nipple from a reputable supplier.
 
Applications 
Machine/Vehicle Construction: Lubricates bearings in engines, suspension systems, or chassis (e.g., cars, trucks).
Agricultural Machinery: Keeps tractor axles or harvester drive shafts running smoothly.
Construction Equipment: Maintains bearings in loaders, excavators, or cranes.
Threads: Ensures lubricated threads for easier assembly/disassembly in machinery.
 
Connection to Adjustable Spanners and Locking Pliers
Adjustable Spanners: Used to install threaded grease nipples (e.g., M6, 1/8” BSP) by gripping the 12mm hex head for secure, leak-free tightening. Their versatility (as you highlighted) makes them ideal for fitting various nipple sizes.
Locking Pliers: Perfect for holding press-in (spigot) nipples during installation or removing stuck/damaged nipples. Their hands-free grip (as you described) is great for multitasking, like aligning a 12mm spigot in a tight space.
 
Practical Insights for 15mm x 12mm, 6g Nipples
Installation:
Threaded: Use an adjustable spanner to tighten the 12mm hex head, ensuring proper torque (typically 5-10 Nm) to avoid leaks.
Spigot: Press into a 12mm hole, using locking pliers to hold or align if resistance is high.
Lubrication: Use a standard grease gun with a 4-jaw coupler. Clean the nipple first to prevent dirt ingress, critical for small 6g fittings in dusty environments like construction sites.
Improvised Repairs: As with locking pliers for stripped bolts, these nipples are key in unorthodox fixes, ensuring lubricated parts don’t seize during maintenance.
Storage: Store the 600g box in a dry place to prevent rust, especially for zinc-plated nipples.
 
New Angle: Compatibility and Selection
Thread/Spigot Sizes: The 12mm width suggests common thread sizes like M6, M8, or 1/8” BSP for threaded models, or a 12mm diameter hole for spigot types. Check machinery specs for compatibility.
Pressure Rating: Most standard nipples handle up to 10,000 psi, but avoid over-pressurizing bearings (keep below 500 psi) to protect seals.
Material: At 6g, these are likely zinc-plated steel, suitable for general use but less durable than stainless steel in corrosive environments (e.g., agricultural settings).
 
Clarifications Needed
“67 cs”: Confirm if this is 67 pieces or another designation (e.g., catalog code or case size).
“S.K.”: Is this a specific brand/model, or should I assume a generic grease nipple? More details (e.g., product code, application like tractor vs. car) would help.
Application: Are you using these in a specific context (e.g., automotive repair, farm equipment) where I can suggest tools or techniques?