I also have ILC-1, which is more expensive version, but it's drop-in module and easy to install,it fits Convoy lights,I'm don't know if it fits S41.
By default there is only one color to choose, but if you want two different colors that is possible since ILC-1 has two separated channels with constant current drive.
I just tried it in my manker E14 (same as S41) and it does not fit.
I think what people who are suggesting links are not understanding is that we want to buy a fully assembled one, ready to go - nothing to do to it.
Thank you for your help though. 
The ILC-0 tailcap switch led4power sells you “only” have to solder the spring. 
If soldering isn’t your thing maybe you could ask him to do it for you.
I am close to finish my new line of tail switch boards in Rainbow and 2x4LED cross pattern
They got both brightness control with a voltage regulator and 2 trimmers for each channel to set them as bright as you desire
You can choose from 12 different colors, it is also possible to use more than 2 colors on the cross pattern boards, as each LED has its own resistor
I will start the sales topic when I have time
Nice I’ll be waitinf
Love the rainbow tailcaps and trimmer adjustment. I’ll definitely be in for 2 of those.
Yep I’m in the queue too! :+1: That rainbow one is fantastic, so is the other lol.
I’d be ok with a spring to solder so I’ll have a look, thanks.
I will set up my sales topic in the next few days
Rainbow would be perfect for my colored S41S
Why doesn’t it work, do you know?
Ok…Sooo…Those weren’t turnkey so where are the lead wires supposed to be soldered to (which I’ll have to have someone else solder)???
I find this thread after just buying these
The rainbow ones look very cool.
Positive wire gets to the tube contact
negative gets to the spring
replace washer with board and just connect to to both switch connections
I guess it could be made to fit as it is close. Diameter is the problem, I think it would fit nicely otherwise. However, myself, I’m not willing to file down the switch nor open up the threads in the tail.
I will soon offer ILC-1 kit without brass ring at significantly lower price than assembled ILC-1, top and bottom pcbs have 16.5mm diameter , so such "ringless" ILC-1 should fit in more lights (brass ring is not really necessary, but without it switch and top pcb should be glued to prevent twisting).
Aah, that makes sense why the brass ring is there 
I can’t see the images
That’s how I see them
Try again…
Did it work?
If not - it’s just a pic of some measuring calipers in the tail cap and on the switch. ID of tail cap = 18.05mm OD of switch = 18.19mm
