Metallics HTB49B Bolts 1/4-20 x 1-1/4 Hx Tap Blt St-zn (Box 2500)

The HTB49B is a 1/4-20 hex tap bolt, so 20 threads per inch in the standard coarse 1/4 inch series. Any standard 1/4-20 hex nut, nylon insert nut, or 1/4-20 tapped channel (strut nut, tapped flange, threaded insert) will mate with it. Tap bolts are threaded the full length of the shank rather than part way, which is why they work well into tapped holes and thinner stacks where a partially threaded bolt would bottom out on the shoulder.

The HTB49B is zinc plated steel, which handles indoor, dry, and occasionally damp service. Zinc plating is a sacrificial coating, not a marine one, so for direct weather exposure, wet wells, coastal air, chemical areas, or anywhere a stainless fastener is specified, go to the 18-8 stainless version of the hex tap bolt instead. Metallics builds this bolt in both steel-zinc and 18-8 stainless, so the same 1/4-20 x 1-1/4 size is available in stainless if the environment demands it.

The HTB49B ships as a box of 2,500 pieces, and 2,500 is the order minimum, so it is a bulk pack meant for a shop crib, a service truck stock program, or a job with repetitive bracket and strut work. Metallics does build this bolt in other sizes and quantities on request, so if you need a smaller count or a different length in the same 1/4-20 thread, that can be sourced rather than buying 2,500.

Across the flats the head measures 0.425 to 0.438 inch, which is a 7/16 inch wrench or socket, the standard head size on a 1/4 inch hex bolt. Corner to corner the head runs 0.484 to 0.505 inch, worth knowing if you are driving these in a tight channel or inside an enclosure where the socket needs clearance to swing.

Functionally they look the same from the head, but a tap bolt is threaded right up to the head while a hex cap screw has an unthreaded grip length under the head. Fully threaded, as the HTB49B is, means you get usable thread no matter how thin the material stack, and it will run all the way down into a tapped hole. If your connection relies on an unthreaded shank bearing in the hole, or the spec calls for a defined grip length, order a hex cap screw instead.

Threads on the HTB series are made to IFI-199 (2014). That is the dimensional spec a submittal reviewer or a QA group will want cited, and it is why these interchange with any other standards-compliant 1/4-20 nut or tapped hole on the job.

A full 2,500 piece box of the HTB49B weighs 51.57 lbs and measures 11.5 by 11.5 by 10.75 inches. That is a one-hand-awkward, two-hand carry, so plan shelf space and keep it off a high rack in a shop crib or on a truck.