The spec three of these pages omit

Four of these kits publish a description of their head:

  • EGO ST1623T — LINE IQ auto-sensing feed during cutting, plus POWERLOAD push-button spool reload.
  • EGO ST1521S — bump-feed advance during cutting, with the same POWERLOAD reload.
  • Worx WG170 — COMMAND FEED, which Worx describes as a patented one-button system that releases line on demand rather than a bump-to-ground head.
  • Craftsman CMCST930P1 — push-button feed advancement; the page uses neither “bump” nor “automatic”.

DeWalt’s DCST970X1, Milwaukee’s 3016-21ST and Echo’s DSRM-2600 say nothing about it. Echo’s silence is the strangest of the three, because the same documentation gives a 1.62 gear case ratio, a 25 mm aluminum operating rod, and a 4,860–9,200 RPM band.

The two EGOs are the clearest warning against inferring the answer. Both carry POWERLOAD, and POWERLOAD is a reloading feature — you feed line in and press a button instead of hand-winding a spool. It says nothing about what happens while you are cutting. The ST1623T adds LINE IQ and advances without an input; the ST1521S, with the identical reload system, is a bump head. One marketing name, two different answers to the question you came for.

Among the four described heads, only the ST1623T’s advances without you doing something. Worx’s and Craftsman’s both wait for a button. That is still a different motion from tapping a spinning head on the ground, but it is not hands-off, and neither company publishes how often it is needed.

Size the pack against the swath, not against the yard

Amp-hours are the number buyers reach for, and on their own they do not answer the question. Swath runs from 12 in on the Worx to 17 in on the Echo.

Those two numbers multiply against each other. A 12 in pass covers roughly seven-tenths of the ground a 17 in pass covers; Craftsman’s narrowest 11 in setting covers about two-thirds. Same lawn, more passes, more elapsed trimming time out of the same battery.

Published runtime is the figure closest to a direct answer, and only three kits here have one:

  • Craftsman CMCST930P1 — up to 75 minutes, footnoted as no-load, low speed, at the 11 in swath setting.
  • EGO ST1623T — up to 60 minutes continuous, with no speed setting or swath stated.
  • Echo DSRM-2600 — up to 54 minutes with the 5.0Ah pack, 26 minutes with the 2.5Ah.

Read Craftsman’s footnote before you read its number. That is not a criticism of the tool; it is a reason not to place 75 minutes next to Echo’s 54 as though they describe the same work.

Echo is the only manufacturer here that publishes runtime for two pack sizes on one tool, and the pair is worth having: 26 minutes at 2.5Ah, 54 at 5.0Ah. Doubling capacity a little more than doubled the stated figure on that tool, under whatever conditions Echo used. It is the closest thing in this evidence to a within-tool read on how capacity scales, which is more useful than comparing two brands’ “up to” claims against each other.

For the four kits with no runtime at all — DeWalt, Milwaukee, Worx and the EGO ST1521S — you are sizing from capacity and swath alone. That is a genuine information gap, not a neutral spec sheet.

What voltage buys, and what it does not

Voltage sets which batteries fit. Echo publishes a 4,860–9,200 RPM motor speed with a 1.62 gear case ratio, Worx publishes a 7,600/min motor no-load speed, Milwaukee publishes a 6,200 RPM maximum speed, and EGO publishes an unlabeled 3,500–5,500 no-load speed. Those figures are not stated on a common basis, so they do not rank against each other. DeWalt publishes a GEAR DRIVE brushless motor, Echo a flexible drive shaft.

The labels also need translating. Craftsman markets V20 as 20V and footnotes it as 18V nominal, which is the same family Milwaukee labels M18. Worx publishes 20V MAX as a rated voltage without stating a nominal figure. At the other end, EGO publishes 56V and Echo publishes 56V nominal with a 50.4V rating — again, the same convention split two ways.

One more spec sits alongside voltage for overgrown work: line diameter. Echo accepts 0.080–0.105 in, the widest published range here, with 0.095 in Silentwist as standard. Milwaukee and DeWalt both take 0.080 in and 0.095 in. Both EGOs run 0.095 in. The Worx runs 0.065 in, the thinnest published diameter in this comparison, with no alternative stated. Craftsman publishes no line diameter for the CMCST930P1.

When the smaller kit is genuinely enough

For a small yard, the EGO ST1521S and the Worx WG170 are the two that make sense on their own terms rather than as compromises. The ST1521S pairs the smallest single pack here, 2.5Ah, with a 15 in swath and a documented bump head, on the same 56V platform as the ST1623T — so a larger pack is a later purchase inside a system you already own. The Worx goes the other way: 12 in of swath, two 2.0Ah packs, and conversion to an edger and mini-mower.

They stop being enough at the point where passes start multiplying. On a property that needs real area covered, 12 in of swath and 2.0Ah per pack work against each other, and 2.5Ah with no published runtime gives you nothing to plan with. That is where the 16 in and 17 in heads and the 5.0Ah and 8.0Ah packs earn their place.

Buy the right SKU, and know what is still unsettled

Three gaps are worth settling with the manufacturer before you commit. Craftsman’s own page describes the CMCST930P1 as brushless in its features text and brushed in its specifications table. EGO does not publish a tool weight for the ST1623T in the sources used here, which is why no weight for it appears anywhere in this guide. And Echo’s published runtime and charge-time figures depend on which pack size the bundle carries, so the pack size in any Echo bundle is worth confirming on the listing.