Slides are sold by material — glass, brass, steel — and that is the part everyone argues about. It is also the part you can change later for the price of a coffee. What you cannot change is whether the thing fits your finger, and that is published as a number on every slide Dunlop makes.
So this page starts with sizing, then reports exactly what the maker does and does not claim about material, because the marketing is more careful than the internet summaries of it.
Sizing, which Dunlop publishes and almost nobody reads
Every Dunlop slide publishes an inside diameter in millimeters and a ring size. Dunlop also publishes a one-page sizing chart with a printable paper ruler and a conversion table: wrap the strip around your finger, read the circumference in millimeters, convert. 57 mm is a ring size 8, 62 mm is a 10, 68 mm is a 12.
Dunlop's own advice on top of that: "We recommend choosing a slide slightly larger than your ring size." And a caveat worth quoting before you order: "All slides are handmade. Actual measurements will vary slightly from slide to slide."
A slide that is too tight cannot be worn for a whole song. One that is too loose wobbles and clanks on the frets. Between those, most players want it snug enough to stay put when the finger points down.
18 to 22 mm
The inside-diameter range across the slides on this page
Four millimeters covers ring size 8 to ring size 12.5. That is the specification that decides whether a slide is playable for you, and it is published for every model.
What Dunlop actually claims about materials
Glass: "a warm, thick tone that accentuates the middle harmonics of your sound". That sentence appears word for word on the regular wall, medium wall and heavy wall glass slides alike.
Brass: "a warm, resonant tone thanks to its authoritatively hefty mass". This is the only tone claim in the range attributed to a physical property.
Chromed steel: "a bright tone and is comfortably lightweight".
The Blues Bottle, which is glass: "a crisp, bright tone", credited to the closed, weighted end — directly contradicting the generic glass line, on the same maker's site.
And the finding that matters most: because the glass tone sentence is identical across every wall thickness, Dunlop makes no published claim that a thicker glass wall changes tone or sustain. Heavier glass gives you more mass and a bulkier object. Any claim beyond that is somebody's opinion, including ours, and we have not played these.
The criteria, in the order they decide it
1. Inside diameter, against your finger
Measure first. Everything else is preference; this one is fit.
2. Length, against how many strings you play at once
Published lengths here are 60 mm for the brass and steel, 68 to 69 mm for the glass models. A longer slide covers all six strings for full chords; a shorter one clears the strings you are not using and is easier to angle.
3. Mass, which is the real material difference
Brass is the heavy option, steel the "comfortably lightweight" one in Dunlop's words, and glass sits between depending on wall thickness. More mass presses the string more easily and is less forgiving if your hand drifts; less mass needs cleaner technique to avoid fret rattle. Note that Dunlop publishes no weight for any slide, so mass here is inferred from material and wall thickness, not read off a spec.
4. Which finger you will wear it on
Third finger keeps two fingers free for fretting; little finger keeps three. Both want a different diameter from your ring finger measurement, which is another reason to measure rather than guess from a ring you own.
5. What your guitar is set up like
Slide playing wants a little more height than fingerstyle, because the slide rides above the frets. If your action is very low you will fight rattle whatever slide you buy — the action page covers measuring it, and the same measurements tell you if you have room to raise it.
Published dimensions, side by side
What Dunlop publishes for each slide| Slide | Material | Inside dia. | Length | Ring size |
|---|
| Dunlop 202 | Glass, regular wall | 18 mm | 69 mm | 8 |
| Dunlop 215 | Glass, heavy wall | 20 mm | 69 mm | 10–11 |
| Dunlop 222 | Brass, medium wall | 19 mm | 60 mm | 9–10 |
| Dunlop 220 | Chromed steel | 19 mm | 60 mm | 9–10 |
| Dunlop 273 Blues Bottle | Glass, 2 mm wall | 22 mm | 68 mm | 12.5 |
No weights, because Dunlop does not publish any. Every figure above is from the maker's own product pages or its sizing chart.
The picks
Dunlop 202 glass — best first slide
Eighteen millimeters inside, ring size 8, 69 mm long and the lowest price here. Glass is the traditional starting point and the thin wall keeps the slide light enough that you can still fret chords with the other fingers while learning.
Against it: least mass of anything here, so it is the most sensitive to pressure and angle. Glass breaks. And stock was thin when we checked.
Dunlop 222 brass — best for weight and sustain
The one slide whose tone Dunlop explains by physics rather than adjective: warm and resonant because of the mass. Sixty millimeters long, 19 mm inside, and it will survive being dropped.
Against it: heavy enough to fret the strings unintentionally when your hand tires, no published weight to compare it by, and metal on wound strings is audibly noisier than glass.
Dunlop 215 heavy wall glass — most glass
Same 20 mm bore as a standard medium glass slide with 29 mm of outside diameter around it. If you want glass character with more mass behind the string, this is how Dunlop sells it.
Against it: bulky on the finger, costs more than the thin-wall glass, and Dunlop does not claim it sounds any different from the thin one.
Dunlop 220 chromed steel — brightest
Dunlop's only bright-and-light description in the standard range, which is why it turns up on electric guitars more than acoustics. Cheap and indestructible.
Against it: Dunlop's own page cannot decide whether it is regular or medium wall, steel is the noisiest material against wound strings, and no weight is published.
Dunlop 273 Blues Bottle — best long reach
A 68 mm medicine-bottle form with a closed, weighted end that Dunlop says balances it, and the largest bore here at 22 mm.
Against it: too large for slim fingers, the most expensive slide here, and Dunlop's description of it as crisp and bright sits oddly against its own claim that glass is warm and thick.
Making a slide sound like music
Play over the fret, not behind it. The slide replaces the fret, so the note is in tune when the slide sits directly above the fret wire.
Use almost no pressure. Enough to touch the strings, not to press them to the board. Pressure is what makes a slide clank.
Damp behind the slide. The fingers behind it mute the string noise that otherwise follows you up the neck.
Heavier strings help. More tension means less rattle under a slide — the gauge guide covers what moving up a gauge does to feel and tension.
What we would actually buy
A first slide: the 202 glass, after measuring your finger against Dunlop's chart. Wanting more weight and sustain: the 222 brass. Playing electric and chasing a bright, cutting voice: the 220 steel. Large hands or full six-string chords: the Blues Bottle. And buy one size up if you are between sizes, as Dunlop itself recommends.
What we did not doWe have not played any of this gear. Every guide in this category says it tested twenty tuners; we would rather say plainly that we tested none. What we did instead is on this page in full: published specifications with their sources, the makers' own manuals read rather than paraphrased, and a note wherever a company publishes nothing at all.
