Ko-ken RS2400MZ/12 Z-series 6.35mm or 1/4″ Socket Set with Rail Review

By /

Looking for a quality set of Japanese-made super shallow 1/4″ drive (or 6.35mm) sockets? Today I am reviewing the Koken RS2400MZ/12 Z-series or Zeal socket set (found on eBay US or eBay AU), often suggested as an alternative to other high-end brands such as Snap-On – read on for my review!

The sockets arrive in a plastic sleeve:

Here is a review of the Ko-Ken or Koken RS2400MZ/12 Z-series or Zeal quarter inch drive or 6.35mm socket set.

The sockets range in size from 4mm to 14mm, as you can see on the outside:

Here is a review of the Ko-Ken or Koken RS2400MZ/12 Z-series or Zeal quarter inch drive or 6.35mm socket set.

Country of origin is also on the same sticker – Made In Japan. Out of the packet, we get a better look at the sockets and rails:

Here is a review of the Ko-Ken or Koken RS2400MZ/12 Z-series or Zeal quarter inch drive or 6.35mm socket set.

The rails are nice – magnets on either end on the underside and the sockets are held in tightly but not so much that they’re hard to remove. The shallow sockets are really quite shallow – here’s one of my most-frequently-used 1/4″ drive sockets in Kincrome’s standard size vs. the Ko-ken shallow:

Here is a review of the Ko-Ken or Koken RS2400MZ/12 Z-series or Zeal quarter inch drive or 6.35mm socket set.

The Koken sockets are 6-point, and have rounded corners to avoid driving on the corners of the fastener:

Here is a review of the Ko-Ken or Koken RS2400MZ/12 Z-series or Zeal quarter inch drive or 6.35mm socket set.

There’s two different shapes – up to 8mm is one style and from 10mm and above is another:

Here is a review of the Ko-Ken or Koken RS2400MZ/12 Z-series or Zeal quarter inch drive or 6.35mm socket set.

9mm is notably absent – though to date I have not come across a 9mm fastener (except approximately when trying to fit metric sockets onto imperial fasteners), so that’s probably not much of a loss. The sockets are finished quite nicely, with a mixture of a satin-like finish and shiny chrome.

The ribbed shape towards the square drive end does make it easier to pull the sockets off whatever they’re attached to:

Here is a review of the Ko-Ken or Koken RS2400MZ/12 Z-series or Zeal quarter inch drive or 6.35mm socket set.

In use the sockets are very, very good. Tolerances are very tight – the sockets seat firmly and have absolutely minimal slop when attached to a drive tool. When combined with a compact driver like the Nepros NBR290 (my review here) or NBS2L (review here) access into really, really tight spaces is greatly improved over using a standard-size ratchet and socket set.

Shallow socket sets aren’t for everybody – but the Zeal range is not limited to just that height, so if you’re after this quality in a different height socket check out their semi-deep set (RS2300XZ/9 is what to look for there on eBay US, eBay AU) and deep (RS2300MZ/12 on eBay US, eBay AU). The tight tolerances on the fastener end of the socket also mean that in tight spaces it’s a bit easier to keep fasteners held in the socket while approaching the threads, which has resulted in me dropping less fasteners into engine bays/bike frames. Most welcome.

If you’re in the market for a quality, 6-sided shallow socket set in 1/4″ drive the Ko-ken 2400MZ/12 set is well worth a look. Find a set on eBay US and eBay AU.

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top