Sig 4-stroke glow plugs

Somehow over the years I picked up a bunch of these glow plugs. Inasmuch as their labels suggest they are '4-stroke' plugs, I assume that they are at the hot end of glow plugs' heat range.
Has anyone had any experience using these plugs, and any comments on their general usability in Stunt engines?

Many thanks.

My thoughts on this type of situation are: if you've got 'em, run 'em. Try your 'normal' one, then switch and run one of these to see the difference. Depending on what you're doing with the plane, they might or might not make a difference. I'm not into that last-ounce-of-thrust type of tweaking, so my glow plugs (I buy whatever's cheap) last quite a while. The gotta-have-the-latest-greatest-innovation guys tend to gawk at my planes "Hey! Did you know your glowplug's rusty? That plane won't run!" but I'm flying while they're tweaking/buying.......

They should work ok on ABC ball bearing "4-2-4 run" engines, at least in cooler weather. You may want to add an extra glowplug gasket to cool them down a little, or increase the castor oil content. I don't see a reason to use an idlebar plug on a 2-2-2 run engine, unless it is very cold. Steve

Peter:
I do not have experience with the Sig 4S in particular, but a number of years ago GMA suggested using Thunderbolt 4S in 4-2-4 engines. I have used them with good results in a Fox 35, a Fox 25 BB and an OS 40 FP and am about to try them in a Stuka Stunt TT 25 GP. I suspect that you will like them, particularly if, as I suspect, you are running high castor fuel.
Peter
(No, there is not an echo.)