2RS vs ZZ bearings: what the seal codes mean, and each maker's equivalent (LLU, DDU, 2RSH, VV, DD)

2RS means rubber seals on both sides of the bearing and ZZ means metal shields. Choose a contact-sealed 2RS against dust and water, and ZZ for speed: bearing makers rate a greased 6203 at 12,000 rpm contact-sealed and 17,000 to 20,000 rpm shielded. We sell 10x 6000 to 6310 2RS and 10x 6000 to 6306 ZZ packs.

If that answers it, you can stop here. The table below gives each maker's code for the same seal, so you can match whatever is stamped on your old bearing.

Each maker's code for the same seal

Source: each maker's own catalogue, designation page and product pages (see Sources), read 2 and 5 October 2026.

Our supplier tells us a DD in a bearing number is a contact seal, so a KBC 6302DD is a contact-sealed 6302. NSK writes DD the same way on its small sizes: it lists the 608DD and 626DD with a rubber contact seal on both sides.

VV is not the same seal as 2RS or DD

Every maker writes its own letters, and the codes that look alike don't always match. The catch is VV. To NSK, VV is a non-contact rubber seal, rated "not suitable" against water. DDU, LLU, 2RS and 2RSH are all contact seals, which bearing makers' catalogues rate highest of the closures against water.

So a title that lists "2RS DD VV" together, as some do, is naming two different kinds of seal. If your job is wet or dirty and the seal type matters, ask us which seal the bearing has before you order.

The second catch is the single letter. Bearing makers also list one-side versions (RS, LU, Z) as well as the two-side ones, so a bearing marked RS or Z may be sealed on one side only. Check both faces of the old bearing.

Is a sealed bearing better than a shielded one?

Not always. A contact seal keeps out more dirt and water, but its lip rubs on the inner ring, which adds friction and lowers the speed limit. A shield doesn't touch, so it runs freer and faster but protects less.

Source: bearing makers' published seal comparison tables and 6203 rows (see Sources), read 2 October 2026.

In short: contact seals give the most protection against dust and water, and shields give moderate protection at high speeds. The light-contact types sit between the two.

The same size in every code

In the 6000, 6200 and 6300 series the seal code doesn't change the size: bearing makers list every closure on one dimension row. A 6203 is 17 x 40 x 12 mm whether it's stamped 6203-2RS, 6203ZZ, 6203LLU or 6203DDU. The sizes people search for most:

Source: bearing makers' published dimension tables (see Sources); the last two columns are from our product listings, 2 October 2026. Every size from 6000 to 6310 is in our bearing size chart.

How to choose the seal code

1. Read the full number off the old bearing, then look at both faces: a seal or shield on one side only is a single-letter code (RS, Z).
2. Match the size first with the size chart. In these series the seal code doesn't change it, but measure the width of very small bearings, since many sealed and shielded miniatures are 1 to 2 mm wider than the open ones.
3. If dust, mud or water can reach the bearing, choose a contact seal (2RS, LLU, DDU, 2RS1 or 2RSH).
4. If the bearing runs fast, close to the speed limits above, or must turn freely, choose a shield (ZZ, 2Z) or a non-contact seal.
5. Read any clearance code separately. C3 means radial internal clearance greater than normal, so a 6205-2RS-C3 is a sealed 6205 with extra internal clearance.

Which BES product fits

• Pick the 10x 6000 to 6310 2RS bearings for rubber seals in any of the 33 sizes. Our listing describes them as rubber seals; if you need a confirmed contact seal, ask us before ordering.
• Pick the 10x 6000 to 6306 ZZ metal shielded bearings if the old bearing was ZZ, or the job is clean and fast. ZZ is listed for 6000 to 6006, 6200 to 6206 and 6300 to 6306.
• Pick the 2x 6005 to 6310 2RS bearings if you need only two of the larger sizes.
• Pick the 10x 604RS to 609RS and 626RS bearings for the small rubber sealed sizes.
• Pick the 10x 608-RS bearings or 10x 608-ZZ shielded bearings for 8 x 22 x 7 mm.

Browse every size in ball bearings.

Questions people also ask

What is 2RS in a bearing?

2RS means a rubber seal on both sides. In Koyo's code it's a contact seal, the type rated highest against water. NTN calls the same seal LLU, and NSK calls it DDU (DD on small sizes such as the 608).

What does RS mean on a bearing?

To Koyo, RS is a rubber contact seal on one side and 2RS is both sides. Some sellers, us included, write RS for a bearing sealed on both sides: our 10x 608-RS lists 608-2RS among its interchange numbers. Check both faces of your old bearing.

What is a ZZ bearing?

A ZZ bearing has a metal shield on both sides. Koyo, NTN and NSK all use ZZ (NSK writes ZZ1 on some small sizes, such as its 608ZZ1); SKF writes 2Z. Z alone is one shield.

Is 2RS1 the same as 2RS?

They're the same kind of seal. 2RS1 and 2RSH are SKF's codes for a rubber (NBR) contact seal on both sides, which Koyo writes as 2RS. So a 6302-2RSH is a contact-sealed 6302, 15 x 42 x 13 mm.

What do DD and VV mean on a bearing?

They're two different seals. On NSK's small bearings, such as the 608, VV is a rubber non-contact seal on both sides and DD is a rubber contact seal on both sides. Our supplier tells us KBC's DD is a contact seal too.

Is a 608ZZ the same size as a 608RS?

Yes. Both are 8 x 22 x 7 mm; ZZ is shielded and RS is rubber sealed. Our 608 bearing guide covers skateboards and scooters.

Related reading

• Bearing size chart 6000 to 6310: bore, OD, width and a reverse lookup
• 608 bearing size, 608ZZ vs 608-2RS, skateboards and scooters
• Thrust ball bearing sizes: 51100 and 51200 series

Sources

• Koyo (JTEKT), Bearing specification tables, CAT. NO. BS004EN: Table 1 "Comparison of shielded and sealed bearing performance", p. B6, and single-row deep groove ball bearings, shielded and sealed type, p. B20 (koyo.jtekt.co.jp/en/support/catalog-download/uploads/catbs004en_b.pdf), read 2 October 2026.
• NTN, Ball and Roller Bearings, Cat. No. 2203/E: Deep Groove Ball Bearings, Table 1 "Sealed ball bearings: construction and characteristics", p. B-17, and dimension tables pp. B-22 to B-27 (ntnglobal.com/en/products/catalog/pdf/2203E_b02.pdf), read 2 October 2026.
• NSK, Deep Groove Ball Bearings: Table 3 "Comparison of seal / shield performance", p. 5, designation chart, p. 7, and dimension tables, p. 10 (nsk.com/content/dam/nsk/am/en_us/documents/bearings-americas/Deep-Groove-Ball-Bearings.pdf), read 2 October 2026.
• SKF, Deep groove ball bearings: Designation system (skf.com/us/products/rolling-bearings/ball-bearings/deep-groove-ball-bearings/designation-system), read 2 October 2026.

Checked against the Koyo, NTN, NSK and SKF catalogues and our product listings on 2 October 2026.