Gear guide
Best medium grit for rock tumbler step 2
Picked from Amazon listings, not hands-on tests. How we pick
Medium grit (step 2, 150/220 silicon carbide; some brands sell 120/220) removes the scratches left by coarse grit. It does not reshape the stone, so step 2 is normally run once, for about 7 days, until the stones are smooth and evenly matte. That makes it a top-up purchase: most buyers need it because a four-step kit ran short on one grade. The packs below are single-step medium silicon carbide only. They differ in the stated grading (150/220, 120/220, 180/220 or a straight 150), in weight from 1 lb to 10 lb, and in the container, which several listings do not describe. Grit is used at about 2 level tablespoons per pound of rock, the same as in step 1, so a 3 lb barrel takes about 4 tablespoons per run. This guide compares the listings by grit, material, weight and packaging. Nothing was tested: every detail comes from the Amazon listings. The grit calculator on this site gives exact amounts by barrel size.
Compare the picks
| Pick | Grit | Material | Weight | Container | Price | Per lb | Link |
|---|---|---|---|---|---|---|---|
 Fundamental Rockhound medium grit 150/220, 5 lb | 150/220 | Silicon carbide | 5 lb | not stated | - | - | Amazon |
 KomeStone medium grit 150, step 2 refill, 5 lb | 150 | Silicon carbide | 5 lb | not stated | - | - | Amazon |
 GANGOU medium grit 120/220, 10 lb container | 120/220 | Silicon carbide | 10 lb | Wide-mouth container | - | - | Amazon |
 MJR Tumblers medium grit 120/220, 2 lb | 120/220 | Silicon carbide | 2 lb | not stated | - | - | Amazon |
 Fundamental Rockhound medium grit 150/220, 1 lb | 150/220 | Silicon carbide | 1 lb | not stated | - | - | Amazon |
 YHAspace medium grit 180/220, 2 lb | 180/220 | Silicon carbide | 2 lb | not stated | - | - | Amazon |
 Twin Pines Trading Post medium grit 150/220, 4 lb | 150/220 | Silicon carbide | 4 lb | not stated | - | - | Amazon |
Facts are taken from each Amazon listing. Prices are checked daily and shown with their date.
If you just want one
- Closest match for the jobFundamental Rockhound medium grit 150/220, 5 lbThe listing states five pounds of medium 150/220 mixed silicon carbide grit for step two.
- Most for the money on paperGANGOU medium grit 120/220, 10 lb containerThe listing states 10 pounds of 120/220 graded silicon carbide grit, labeled medium.
- Most complete listingKomeStone medium grit 150, step 2 refill, 5 lbThe listing states 150 grit silicon carbide for step 2 medium grinding, in a 5 lb refill.
The picks in detail
Pick 1 · The Fundamental Rockhound
Fundamental Rockhound medium grit 150/220, 5 lb
See price on AmazonFive pounds of medium 150/220 mixed silicon carbide, labeled step two. The standard grading in a mid-size pack for anyone who tumbles batch after batch.
What the listing offers
- The listing states five pounds of medium 150/220 mixed silicon carbide grit for step two.
- The listing describes it as graded grit that is made in the USA.
- Listed as suitable for all brands of rock tumblers.
Limits to know
- The listing does not say whether the 5 lb ships in a bag, a jar or a tub.
- Three short bullets only: no usage amounts or instructions are given.
Pick 2 · KomeStone
KomeStone medium grit 150, step 2 refill, 5 lb
See price on AmazonA 5 lb step 2 refill of straight 150 grit silicon carbide. The listing gives a usage ratio, which makes it easier to work out how many batches the pack covers.
What the listing offers
- The listing states 150 grit silicon carbide for step 2 medium grinding, in a 5 lb refill.
- Gives a usage ratio: about 1 oz of grit per pound of rocks, for up to approximately 80 lb of rocks.
- Listed as compatible with most standard rotary and vibratory rock tumblers.
Limits to know
- Graded as a single 150 grit, not the 150/220 blend named in most step 2 instructions.
- Container type and country of origin are not stated in the listing details used for this guide.
Pick 3 · GANGOU
GANGOU medium grit 120/220, 10 lb container
See price on Amazon10 lb of 120/220 graded silicon carbide for step 2 in a wide-mouth container. A bulk pack for large barrels or for a club or classroom that runs many batches.
What the listing offers
- The listing states 10 pounds of 120/220 graded silicon carbide grit, labeled medium.
- The listing says the grit is packaged in a wide-mouth container.
- Listed for smoothing rock surfaces after initial shaping (step 2), with any brand of tumbler.
Limits to know
- 10 lb of medium grit is a lot for a step that is normally run once per batch.
- Graded 120/220, not 150/220, and no country of origin or usage amounts are stated.
Pick 4 · MJR Tumblers
MJR Tumblers medium grit 120/220, 2 lb
See price on Amazon2 lb of 120/220 silicon carbide for the second stage. The listing calls it fine stage 2 grit, but the grading is the medium range used for step 2.
What the listing offers
- The listing states 120/220 grit silicon carbide for the second stage of rock tumbling, in a 2 lb size.
- Listed as suitable for most rock tumblers, including rotary and vibratory models.
- The listing says it is offered by a USA-based, disabled and veteran-owned company.
Limits to know
- Graded 120/220, a slightly wider blend than the 150/220 that many step 2 instructions name.
- The title calls it fine grit, which can be confused with step 3, and the container is not stated.
Pick 5 · The Fundamental Rockhound
Fundamental Rockhound medium grit 150/220, 1 lb
See price on AmazonOne pound of medium 150/220 mixed silicon carbide. The smallest pack in this guide, sized for topping up a four-step kit that ran short on step 2.
What the listing offers
- The listing states one pound of medium 150/220 mixed silicon carbide grit.
- The listing describes the grit as graded and made for rock tumbling.
- A 1 lb size, the smallest single-step medium pack among the listings compared here.
Limits to know
- Only two short bullets: the container and the country of origin are not stated.
- At 1 lb it suits a top-up for a small barrel, not a long series of batches.
Pick 6 · YHAspace
YHAspace medium grit 180/220, 2 lb
See price on Amazon2 lb of 180/220 graded silicon carbide, labeled medium and step 2. A small refill with a narrower, slightly finer grading than the usual 150/220.
What the listing offers
- The listing states 2 pounds of 180/220 graded silicon carbide grit, labeled medium.
- Listed for smoothing rock surfaces after initial shaping (step 2).
- Listed as compatible with any brand of rock tumbler.
Limits to know
- Graded 180/220, a narrower and slightly finer blend than the usual 150/220.
- The listing does not describe the container or give usage amounts.
Pick 7 · Twin Pines Trading Post
Twin Pines Trading Post medium grit 150/220, 4 lb
See price on Amazon4 lb of medium 150/220 silicon carbide from Twin Pines Trading Post. The grading is the standard one for step 2, but the listing says almost nothing else.
What the listing offers
- The listing states 150/220 silicon carbide grit, the grading most step 2 instructions name.
- Sold as a 4 lb pack, a size between the small top-ups and the 10 lb bulk pack in this guide.
- The title labels it plainly as medium grit, with no other steps mixed into the pack.
Limits to know
- The listing has a single bullet: no container, origin or usage details are given.
- The listing says nothing about tumbler compatibility or rotary and vibratory use.
Read before you buy
- Rock tumbler grit substitutes: what works and what failsSand, aquarium gravel, crushed glass, baking soda and no grit at all, each with a verdict. Only silicon carbide (Mohs 9 to 9.5) cuts quartz-hard rocks.
- How to make sea glass in a rock tumbler: grit, amounts and timingMake frosted sea glass in a rock tumbler: barrel 2/3 full, 2 tablespoons of coarse grit per pound, 3 to 7 days, no polish step. Recipe table and safety.
Tumble Grit chooses every product independently from what its Amazon listing states. We may earn a commission from the links above. As an Amazon Associate I earn from qualifying purchases.