Metallics JMHTB425 Bolts M4 x 25 C8.8 Hx Tap Blt St-zn (Jar 100)

It's an M4 metric thread with a 0.7 mm pitch, right hand, so it threads into any standard M4 x 0.7 nut or tapped hole. The shank is 25 mm long with threads running the full length up to the washer face under the head, which is what makes it a tap bolt rather than a partially threaded hex cap screw.

Class 8.8 is the medium carbon, heat treated grade, and these are rated at 120,350 psi minimum tensile and 95,700 psi minimum yield, with a hardness of Rockwell C23-34. Metallics lists motor mounting to machinery as a primary use, along with automotive and truck repair work. For structural or high-vibration mounting, use it with a hardened washer and a matching Class 8 or better nut so the nut is not the weak point.

No. The JMHTB425 is not Buy American compliant and is not ARRA compliant, with country of origin listed as multiple. On a project carrying domestic sourcing requirements you will need to source a fastener certified to those provisions.

Sold as a jar of 100 pieces, and the jar is the minimum order unit. Total packed weight is 281 g. If you need a different size or a different count, Metallics offers other sizes and quantities in the MHTB and JMHTB series by request.

The JMHTB425 is medium carbon steel with a zinc plated finish. Zinc plating is a mild corrosion barrier meant for indoor and sheltered use, which covers the electrical, plumbing, heating and air conditioning work these are catalogued for. For sustained outdoor exposure, washdown areas, or anywhere salt is present, step up to stainless or hot dip galvanized hardware instead.

A tap bolt is threaded the entire shank length right up under the head, so the full 25 mm of a JMHTB425 is usable grip whether you are running it into a tapped hole, a channel nut, or through a thin flange with a nut on the back. A hex cap screw has a plain unthreaded shoulder below the head, which is better where you want the shank to take shear in a reamed hole but useless if you need thread engagement close to the surface. For thin sheet metal, enclosure flanges, and shallow tapped holes, the tap bolt is the one you want.

Not for the bearing surface itself. The hex head is formed with an integral washer face beneath it, which gives a flat, clean seat against the work. A separate flat washer is still worth adding over soft material, oversized holes, or slotted channel, and a hardened washer is standard practice when you are pulling an 8.8 bolt to full torque.

The JMHTB425 is a hex head bolt, and a standard M4 hex head takes a 7 mm wrench or socket. The head is a plain external hex, so a 7 mm combination wrench, socket, or nut driver all work, and there is no drive bit to strip.