This was the first button I bought as a beginner and still use it indoors after 5 years. Its still as smooth as the day I first bought it and have had no problems other than the usual wear on tip of the Nylon plunger.
You get (or ,at least, you did, not sure if this is still the case!) a choice of two plungers with this button, one nylon and the other steel and although they claim to give you a set of three different rated springs (soft, medium and hard), I only found two in the box and could not distinguish between them at all leaving me to source a stiffer spring when I increased my bow weight.
In spite of this it has never let me down and has remained as smooth as new due to the nylon liner in the barrel and a good close fit keeping dirt and other foreign objects at bay.
The collar on the barrel came with a threaded bar as well as the locking grub screw to aid tight fitting and I leave this in place for that purpose. The adjustment is by means of a screw only so you have to "give it a turn and try it" but once adjusted it stays put after locking it with the grub screws provided.
Importantly, It's easy to dismantle for cleaning without disturbing the setting at all.
It's cheaper than the Shibuya DX and the ideal button for those on a budget and for Beginners to cut their teeth on.
There may be variable quality issues as it is produced down to a price but For the money, I can't fault it.