ANEX Offset Adapter Guide: AOA-19, AOA-30 and AOA-30L Compared (Plus AKL Right-Angle Adapters)

The problem: Some bolts just aren't reachable. A spanner fits into the gap, but there's no room to swing it. A power driver would spin it in seconds, but the socket sticks out too far to fit. Every extra minute hand-turning a bolt one click at a time is time you don't get back, and on jobs with high-torque hardware, hand tools alone may not even get the fastener properly seated.

The solution: ANEX, a Japanese hand tool maker, builds a line of offset adapters built specifically for this problem. Instead of driving straight through, an internal gear routes a power driver's torque sideways, so the tool itself can sit outside the gap while the socket end reaches the bolt inside it. The lineup splits by bolt size and torque rating, and most people land on the brand name without knowing which model actually fits their job — that's what this guide is for.

Quick answer: For 19 mm bolts, the AOA-19 is the adapter alone, the AOA-19S1 adds 17 mm and 21 mm sockets, and the AOA-19S2 is the full offset adapter socket set with eight sockets from 10 to 24 mm, a gear lock and a case. For 30 mm bolts and higher torque, choose the AOA-30 (500 N·m) or the longer AOA-30L.

ANEX offset adapters at a glance

All six are made in Japan. The AOA-30 and AOA-30L accept a 6.35 mm hex or a 9.5 / 12.7 mm square drive on the input side.

ANEX AOA-19 Offset Adapter ANEX AOA-19S1 Offset Adapter with Socket Set

AOA-19 — for 19mm bolts in gaps only a spanner fits

The head is just 9.5mm thick — thin enough to slide into the same gap a hand spanner uses. It's built for 19mm bolts and nuts in framing and structural steel work, like furring channels, purlins, and stud-to-track connections, and it's rated to 180 N·m. Compatible with 18V and 40V impact drivers. 232mm long, 325g.

AOA-19S1 — the 19mm adapter with sockets included

Same 19mm body and 180 N·m rating as the AOA-19, but with two dedicated sockets (17mm and 21mm) and a pair of C-rings included. If your job mixes 17mm, 19mm, and 21mm hardware — common on furring and stud connections — this set covers all three sizes without switching adapters mid-job. 232mm long, 395g with the sockets.

AOA-19S2 — the complete 19mm offset adapter socket set (10–24 mm)

The same 9.5 mm-thick 19 mm body as the AOA-19, sold as a full set: eight dedicated sockets (10, 12, 13, 14, 17, 19, 21 and 24 mm), a gear lock, two C-rings and a storage case. Japanese retailer listings give the body's maximum torque as 180 N·m, say it works with 18V impact drivers, and describe the gear lock as the part that lets you turn bolts by hand. Choose this set when you can't predict the bolt sizes before you get to the job: one thin body covers eight sizes. The set weighs 802 g.

Will it fit your gap? The body is 9.5 mm thick, so in our reading of the spec the space beside the fastener needs to be at least 9.5 mm wide for the head to slide in.

AOA-30 — for large bolts that need real torque, not just access

A 20mm-thick head and a 500 N·m torque rating — over 2.5x the 19mm line — while keeping the same offset-gear mechanism. Built for 30mm bolts, oversized nuts, and threaded rod work where you need both access and grip strength. ANEX specifies that impact wrenches exceeding 500 N·m can damage the adapter, so it's worth staying within its rated range. 730g.

AOA-30S1 — the 30mm adapter with five sockets included

Same 30mm body and 500 N·m rating as the AOA-30, bundled with five dedicated sockets (H24, H27, H30, H32, H36) and two C-rings. One adapter body covers a much wider range of fastener sizes on site — useful when a job mixes equipment mounts with structural bolts. Note that C-ring installation needs a snap-ring pliers, sold separately.

AOA-30L — when even the AOA-30 can't reach deep enough

A long-reach version of the 30mm adapter, for fasteners set further back than any standard offset adapter can reach — rail maintenance work, deeply recessed structural bolts, fastener runs well behind an obstruction. Same 500 N·m torque rating and 30mm output as the AOA-30, just built to go deeper. 378mm long, approx. 1kg.

Offset adapter or right-angle adapter?

ANEX also makes the AKL series of right-angle adapters. They solve a different problem: they hold a 6.35 mm (1/4") hex bit, so they are for screws in tight spots with an electric screwdriver, not for bolts and nuts. If you are driving bolts with a socket, you want an offset adapter from the AOA series above.

ANEX AKL-565 Super Short Right-Angle Adapter ANEX AKL-560 Super Mini Right-Angle Adapter for Electric Screwdrivers

Quick reference: which one do you need?

• Single-size 19mm bolts (furring, framing) → AOA-19
• Mixed 17/19/21mm bolts on the same job → AOA-19S1
• Bolt sizes from 10 to 24 mm, or sizes you can't predict before the job → AOA-19S2
• Single-size 30mm bolts needing high torque → AOA-30
• Mixed H24–H36 hardware on the same job → AOA-30S1
• A fastener set too far back for the standard AOA-30 to reach → AOA-30L
• Screws (not bolts) in a tight corner with an electric screwdriver → an AKL right-angle adapter

Frequently asked questions

What is an offset adapter?

An offset adapter uses an internal gear to move the drive sideways, so a power driver can turn a bolt that sits in a gap too narrow for the driver itself. ANEX makes them for 19 mm and 30 mm bolts.

What is an offset adapter socket set?

It is the adapter body sold together with dedicated sockets. For the 19 mm body, ANEX offers the AOA-19S1 (17 mm and 21 mm sockets) and the AOA-19S2 (eight sockets from 10 to 24 mm, with gear lock and case). For the 30 mm body, the AOA-30S1 includes five sockets from H24 to H36.

Which ANEX offset adapter fits a 19 mm bolt?

The AOA-19 fits H19 bolts and nuts. The AOA-19S1 adds 17 mm and 21 mm sockets for mixed hardware, and the AOA-19S2 covers 10 to 24 mm.

What is the difference between the AOA-30 and AOA-30L?

Both take H30 fasteners. The AOA-30L is longer (378 mm against 284 mm) to reach fasteners set further back, and weighs about 1 kg against 730 g.

Does the 19 mm adapter come with sockets?

The AOA-19 does not. The AOA-19S1 includes 17 mm and 21 mm sockets and two C-rings; the AOA-19S2 includes eight sockets, a gear lock, two C-rings and a case.

Do you need two hands to use one?

Usually, yes. In a FARM SHOW magazine piece on the ANEX offset adapter, a reviewer pointed out that it takes one hand on the adapter and one on the driver. The same piece mentions a user who found it a good replacement for a hand ratchet in a space that only allows one or two clicks.

Can it run nuts down threaded rod?

FARM SHOW notes that the gear drive works with pass-through sockets on threaded rod and long bolts. Check the socket's inner diameter against your rod first: for example, Joshin lists the AOA-1919 (H19) socket with a 14.5 mm inner diameter. Inner diameters for the other sockets are Not confirmed here.

Sources

• TRUSCO Orange Book: AOA-19S2 (dimensions, set contents, weight, country of origin)
• Japanese retailer listings for AOA-19S2 (maximum torque 180 N·m, 18V impact drivers, gear lock)
• Joshin web: AOA-1919 socket (inner diameter 14.5 mm)
• FARM SHOW: Offset Socket Extension Gets In Tight Places