Certina KF 360 Bumper Clamshell: Prototype or Rare?

naurislota · May 9, 2026

Hello, any information please. Inside is kf360. Sorry for poor english. Watch is in servise at a moment. Winding stem is split. Winding crown is with external thread. Back cover is monolithic. Does serial numbers dates watch to 1946? Is it prototype? Bought from Italy. Thank you regardless.

Tony C. · May 9, 2026

Photos are necessary in order to receive useful responses.

naurislota · May 9, 2026

N naurislota
Hello, any information please. Inside is kf360. Sorry for poor english. Watch is in servise at a moment. Winding stem is split. Winding crown is with external thread. Back cover is monolithic. Does serial numbers dates watch to 1946? Is it prototype? Bought from Italy. Thank you regardless.

Screenshot_2026-04-12-14-58-17-223_com.miui.gallery.webp

naurislota · May 9, 2026

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Tony C. · May 9, 2026

Thanks. There is no evidence that it is a "prototype". The KF 360 was the first "bumper"-wind movement used by Certina, and it was introduced in 1947.

So it appears to be a nice, genuine, original example, though photos of the movement would help to confirm. The "clam-shell" style case is also desirable amongst some collectors.

naurislota · May 9, 2026

Tony C.
Thanks. There is no evidence that it is a "prototype. The KF 360 was the first "bumper"-wind movement used by Certina, and it was introduced in 1947.

So it appears to be a nice, genuine, original example, though photos of the movement would help to confirm. The "clam-shell" style case is also desirable amongst some collectors.

There is no evidence becouse there is no archives? As i told watch is on servise. I asked watchmaker to make photos of invisible sides of this watch. I have never seen bumper in rectangular (30x30, 42 between lugs) case. Have you? Does numbers starting 977 goes to 1947? Thank you.

naurislota · May 9, 2026

I'm looking to understand the watch's significance and value, rather than just its market price.

Dan S · May 9, 2026

Nice watch, and welcome to the forum. The case looks fully stamped and marked, so I don't know why one would speculate about it being a prototype. Probably just a fairly uncommon watch. The case design looks very similar to the earlier Schmitz Freres case style often seen on late 1930s tank watches.

naurislota · May 9, 2026

What about brevet stamp? Does it realy is Schmitz Freres or other brand case? I am not speculating. Just looking for truth. Prototype is a question to experts.

naurislota · May 9, 2026

By the way, the casing is milled

naurislota · May 9, 2026

Even if it’s a production model, show me a second one in the same configuration.

naurislota · May 9, 2026

The reference number is 36006.1. '36' clearly designates the KF 360 bumper movement, and '006' is the specific case design. Combined with the 977xxx serial number, this proves the watch was manufactured in 1946.""This is not a 'random' case. It was purpose-built for Certina's first automatic movement before the official 1947 launch.""If you think it's 'ordinary', please provide a catalog reference for the 36006 model.

Tony C. · May 9, 2026

You're being naïve. I could show you several watches in my collection that you won't find other examples of. That simply means that they are uncommon, or rare. It is not evidence of a prototype.

You are also misunderstanding serial numbers. It is common for movements to made dated earlier than when the watches themselves were sold. The KF 360 was first sold in 1947, but that doesn't mean that the movements suddenly appeared that year.

Again, there is no evidence, or even suggestion that your watch is a prototype.

naurislota · May 9, 2026

To clarify, I am not claiming this is a prototype; I am here to ask the experts if the evidence points in that direction.

naurislota · May 9, 2026

While I agree that rarity doesn't automatically equal 'prototype', the combination of factors here is what raises the question. Regarding the serial numbers: the 977xxx is on the case, not just the movement. While movements often predate the final assembly, having a purpose-built case (Ref. 36006.1) stamped with a 1946 serial for a movement that officially debuted in 1947 is a very narrow window. It suggests this wasn't just a 'parts bin' assembly, but a coordinated early production.I’m not married to the word 'prototype.' If 'rare, early production variant' is a more accurate term, I’m happy to use it. However, the technical execution of this square clamshell—milled steel, screw-down crown, and a split stem for Certina’s first-ever automatic—certainly puts it in a different category than a standard production piece.

Tony C. · May 9, 2026

😂

No it doesn't. Parts are always manufactured before models are introduced!

There is nothing that you have said, or shown, that suggests that it may be a prototype.

"rare, early production variant" is a different thing.