Class 15 Bobbin: Size, Class 15 vs Class 66, and What Your Machine Takes

Sewing machine bobbin sizes, as SINGER publishes them

SINGER’s help page is the clearest size chart we found from a machine maker. It lists a height, a diameter and a shape for each bobbin:¹

Bobbin sizes on SINGER's help page

Bobbin	Height	Diameter	Shape
Class 15, transparent	7/16 in (12 mm)	13/16 in (21 mm)	Top and bottom completely flat
Class 15, metal	7/16 in (12 mm)	13/16 in (21 mm)	For models that come with this style
Class 15J	6/16 in (11 mm)	3/4 in (20 mm)	Very slightly curved, slight blue tint
Class 66, transparent	5/16 in (10 mm)	13/16 in (21 mm)	Top and bottom both curved
Class 66, metal	not printed here	13/16 in (21 mm)	Curved top and bottom, specific models only
Metal, for the 221, 221K, 222 and 301	1/4 in (7 mm)	7/8 in (23 mm)	Like Class 15 but shorter

Brother prints a slightly different metric figure for the same 7/16 inch: its Class 15 type bobbin is “11.5 mm (7/16 inch)” high.² The two makers print different metric figures for the same fraction, and neither page we read says its bobbins fit the other’s machines.

L style and M style are names used by thread makers for pre-wound bobbins.¹⁰ No machine maker’s page we read gives their dimensions, so we don’t print any. See our bobbin thread guide for pre-wound bobbins.

Class 15 vs Class 66 vs 15J: don’t swap them

SINGER is blunt: “Class 66, Class 15 and Class 15J bobbins are very similar. However, using the wrong type of bobbin in your machine can cause damage.”⁶ Its chart adds a “do not substitute” line to every Class 15, 15J and 66 row, including between plastic and metal bobbins of the same class.¹

Two more rules from the same page: use only the class and style that came with your machine, and “If a bobbin becomes chipped, bent, warped or damaged, discard it & replace with a new bobbin.”¹

If the thread is already nesting under the fabric, see our guide to bobbin jamming.

Which bobbin your machine takes, by brand and model

Each row is what the maker writes for that model. A model that is missing was not read.

Bobbin named by the maker, model by model

Machine	Bobbin the maker names
Brother XM2701, LX3817	SA156 (XM2701 manual: 11.5 mm; LX3817 manual: “Class 15 type bobbin”)7,11
Brother CS7000X	SA156, “Class 15 type bobbin”, 11.5 mm (7/16 inch)2
Brother SE700, SE725, LB5500, SE2000, PE545	Plastic SA156, “a Class 15 type bobbin”, 11.5 mm3,12,13
Brother PR1055X, PR1060W (10-needle)	Pre-wound Fil-Tec bobbins or metal bobbins made for the machine14
Brother PR600II, PR620, PR650, PR655, PR1000, PQ1500SL	SA159 metal bobbins15
Brother PE-100 to PE-300S, CS8072 and other older models	SA155, “9.4 Size”, 3/8 inch deep16
SINGER Heavy Duty line	“the same Class 15 bobbin as all other Heavy Duty models”4
SINGER Heavy Duty 6800C, HD4552	SINGER Class 15 transparent only17,18
SINGER M3200 to M3500	SINGER Class 15 bobbins19
SINGER 66-1 to 66-18, 99CL, 185, 192, 201, 609, 717	Class 66 metal20
SINGER 221, 221K, 222, 301	Their own short metal bobbin1
Janome Memory Craft 8900QCP, 500E LE	Janome plastic bobbins for horizontal hook, marked “J”5,8
bernette b38	“J” plastic bobbins for horizontal hook21
JUKI HZL-L series	“designated plastic bobbins for horizontal hook” (no class named)22
BERNINA 335	“Bobbin for CB Hook” (no class named)23
HUSQVARNA VIKING Emerald 116, 118, 122, Jade 20, Designer Jade 35	Its own “Bobbin Plastic 15 Class”24

Three things stand out:

• Brother bobbin size: the home sewing and embroidery manuals we read, outside the PR line, all name the SA156. Brother’s help page for its CE and CS models says the same in other words: “You should be using a standard Class 15 bobbin.”²⁵ Older embroidery models and the PR and PQ lines take other bobbins.
• Janome bobbin size: Janome writes “J”, not “Class 15”. A thread maker’s chart puts “Janome: All Models” under its A style, but that is the thread maker’s statement, not Janome’s.¹⁰
• SINGER Heavy Duty 4452 and 4423: their manuals list bobbins without naming a class; the Class 15 statement comes from SINGER’s help pages.⁴

Metal or plastic

Follow the machine, not a general rule. SINGER’s Canadian store says plastic bobbins “are lightweight and won’t damage top drop-in bobbin cases”, and adds: “It’s important to use the bobbin type recommended for your machine.”²⁶ Yet SINGER also sells Class 66 metal bobbins for older top drop-in models, so “plastic for drop-in” is not universal.²⁰

On Brother machines, clear bobbins have a second job: they “ensure that the bobbin thread sensor is activated when bobbin thread is broken or running low.”⁹

If the bobbin case itself is damaged, see our bobbin case guide.

Genuine bobbins, by machine

We have not tested these: each is the part the maker names for the machines listed.

Class 15 type, for Brother home machines

Brother SA156

Type

Class 15 type, clear plastic

Height

11.5 mm (7/16 inch)

Pack

10 bobbins

Strengths

• Named by part number in the manuals
• Clear, so the bobbin thread sensor works, says Brother
• Listed by Brother Canada

Drawbacks

• On Amazon.com we found it only as a pack of two boxes, so we link to Brother
• Could not be ordered on Brother’s US store when we checked, on 2026-11-11

Good fit: your Brother manual names the SA156, as the XM2701, CS7000X and SE700 manuals do.
Skip it if: you own a PR or PQ machine, or an older model that takes the SA155.

Class 15 transparent, sold in Canada

SINGER 15 Class Plastic Bobbins, 10-pack

Style

Class 15, transparent plastic

Pack

10 bobbins

Store

SINGER Canada

Strengths

• On SINGER’s Canadian store
• SINGER lists other brands that use a plastic Class 15 bobbin

Drawbacks

• We did not find this 10-pack on SINGER’s US store

Good fit: you are in Canada and your SINGER takes a plastic Class 15 bobbin.
Skip it if: your machine came with metal, Class 15J or Class 66 bobbins.

For older SINGER top drop-in models

SINGER Class 66 Metal Bobbins, 4-pack

Style

Class 66, metal

Pack

4 bobbins

SINGER lists

66-1 to 66-18, 99CL, 185, 192, 201, 609, 717

Strengths

• The models are named by SINGER
• Metal, as these machines require

Drawbacks

• Not for machines that take transparent Class 66
• Not found on SINGER’s Canadian store

Good fit: you sew on one of the vintage SINGER models that SINGER lists for Class 66 metal.
Skip it if: your machine uses Class 66 transparent bobbins: SINGER says not to substitute.

9.4 size, for older Brother embroidery models

Brother SA155

Size

9.4 Size, 3/8 inch deep

Material

clear plastic

Pack

10 bobbins

Strengths

• Brother publishes the list of models
• Shows that not every Brother takes the SA156

Drawbacks

• Some PC and ULT models appear on two Brother bobbin lists: check the manual
• Not found on Amazon.com

Good fit: your model is on Brother’s list for the SA155, such as the PE-150 or the CS8072.
Skip it if: your manual names the SA156: the SA155 is shallower.

Metal, for PR and PQ machines

Brother SA159

Material

metal

Pack

5 bobbins

Brother lists

PQ1500SL, PR600II, PR620, PR650, PR655, PR1000

Strengths

• Named by Brother for these models

Drawbacks

• On Amazon.com we found only other brands’ bobbins citing this part number

Good fit: you own one of the PR or PQ models on Brother’s list.
Skip it if: you own a home sewing or combo machine that takes the plastic SA156.

For Emerald and Jade models

HUSQVARNA VIKING Bobbin Plastic 15 Class

Style

15 Class, plastic

Listed for

Emerald 116, 118, 122; Jade 20; Designer Jade 35; others

Note

Onyx and Emerald 203, 183 take another item

Strengths

• Models named on the page

Drawbacks

• Two different 15 Class items exist for the brand
• The Canadian page sends you to the US store

Good fit: you own one of the HUSQVARNA VIKING models the page lists.
Skip it if: you own an Onyx or an Emerald 203 or 183: the maker sells a different 15 Class bobbin for them.

Buying in Canada

• Brother: Brother Canada lists the SA156.²⁷
• SINGER: the 10-pack of Class 15 plastic bobbins is on SINGER’s Canadian store; we did not find the Class 66 metal 4-pack there.²⁶

Our Amazon link goes to Amazon.com. From Canada, check delivery and import fees on the listing before you order.