Metallics JMHTB6121 Bolts M6 X 12 C10.9 Hx Tap Blt St-zn (Jar 100)

It's an M6 bolt 12mm long with a 1.0mm thread pitch, which is standard metric coarse for M6. The threads run the full length of the shank right up to directly beneath the head, so there is no unthreaded grip section. That full thread is what makes it a tap bolt rather than a partially threaded hex cap screw, and it's what you want when you're threading into a tapped hole or a nut and need engagement over the whole 12mm. Thread direction is right hand.

Class 10.9 is the step up from 8.8 in the metric property class system, and these Metallics tap bolts are rated at 150,800 psi minimum tensile and 136,300 psi minimum yield. Hardness runs Rockwell C32-39. The material is high alloy steel, heat treated. Where a joint is loaded hard enough that an 8.8 fastener won't hold the clamp load, 10.9 is the usual answer, which is why these see service in automotive and fleet work. Don't substitute an 8.8 into a 10.9 application.

These M6 x 12 class 10.9 tap bolts ship 100 to a jar, and 100 count is the order minimum, so the jar is the smallest unit sold. Metallics does offer other sizes and quantities by request if 100 of this size isn't what the job needs.

The hex head on these bolts is formed with a washer face underneath it, so there is a finished bearing surface against the work without adding a washer. On softer or coated material, or where you want to spread the load over a larger area or protect a finish, a flat washer is still worth adding. The washer face isn't a substitute for a lock washer if the joint needs vibration resistance.

The finish is zinc over steel, which is a mild corrosion barrier for indoor, enclosed, or dry service. It is not stainless and it is not hot dip galvanized, so sustained outdoor exposure, washdown, or salt will eventually get through it. For permanently wet or coastal work, step up to a stainless or hot dip galvanized fastener instead. Also keep in mind that high strength plated bolts should not be mixed with dissimilar metals in a damp joint without isolating them.

Shank outside diameter is specified at 5.82 to 6mm, which is nominal M6. Head height runs 3.85 to 4.15. Across that geometry a standard metric socket or wrench for an M6 hex head fits; the bolt is driven from the hex head, not a recess. For a clearance hole, M6 normally takes a 6.5 to 7mm drill depending on how much float the joint needs.

Both belong to the same Metallics MHTB and JMHTB hex head metric tap bolt family. The J prefix on JMHTB6121 identifies the jar-packed version; the bolt itself is the M6 x 12 class 10.9 zinc plated steel tap bolt either way. Order by the exact part number if the packaging format matters to how you stock it.

These are made in China. If you're buying against a domestic-sourcing requirement on a public project, that's the figure your submittal needs.

A full jar of 100 weighs 481 grams, a little over a pound. Useful if you're building out a van stock or a shop bin and counting shipping weight across a parts order.