Metallics JMHTB1220 Bolts M12 x 20 C8.8 Hx Tap Blt St-zn (Jar 50)

It is an M12 bolt with a 1.75 mm thread pitch, right hand, which is the standard coarse metric pitch for M12. It will thread into any M12 x 1.75 tapped hole or nut. The shank is 20 mm long and threaded all the way up to the underside of the head, so the full 20 mm of engagement is usable.

Yes, that is the job it is built for. Class 8.8 is medium carbon steel, heat treated, with a minimum tensile strength of 120,350 psi and minimum yield of 95,700 psi, hardness Rockwell C23-34. That is the common structural-grade metric bolt for motor mounts, equipment feet and machinery brackets, and it is also widely used in automotive and truck repair.

A tap bolt is fully threaded, right to the washer face under the head, while a standard cap screw has a plain unthreaded shoulder below the head. The full thread is what you want when the bolt is going into a tapped hole of unknown or shallow depth, or when you are clamping a thin stack and need thread engagement all the way through. On a 20 mm long M12 like this one, a partial thread would leave almost nothing to engage, so fully threaded is the right form for short lengths.

The finish is zinc plating on steel, which handles indoor service, mechanical rooms and sheltered equipment well. It is not a marine or sustained-wet finish; for exposed exterior work, roof curbs or washdown areas, step up to hot dip galvanized or stainless. For electrical, plumbing, heating and air conditioning work, which is what this bolt is stocked for, zinc plated is the normal choice.

Fifty bolts, packaged in a jar, and 50 each is the order minimum. That jar packaging is what the J prefix on JMHTB1220 denotes within the MHTB and JMHTB series. The filled jar weighs 1,515 g.

The head has an integral washer face underneath it, so the bearing surface is already flat and finished. A separate flat washer is still worth adding over soft material, oversized holes or slotted channel, and a lock washer or thread locker if the joint sees vibration. Washers and nuts are not included in the jar of 50.

Other sizes and quantities in the MHTB and JMHTB hex tap bolt series are available by request. The JMHTB1220 specifically is the M12 x 20 mm in a 50 count jar; longer shanks and larger pack counts run under the same series.