(Assuming you're talking about the ones for your thumb) For me, the vinyl ones get/are too tacky/sticky. The urethane ones stay smooth; I sand them to fine-tune them for my thumb. Sometimes I have to sand them lightly to reduce the smoothness. I prefer the urethane ones for abetter, more consistent feel.

I think we're on to exactly what I am seeing. However, how does one look at an existing slug and ID which type it is? For example, last night I was sticking in the thumb hole and noticed that the slug seemed markedly tackier than what I remember from when I was using IT. When I went home, I felt the same impression. OK, so that means the current is Vinyl and the previous was urethane, but is there any way to visually identify that for sure? Is there anything other than smooth and slick vs rough and tacky by comparison? In fact, looking at them now, my old batch are very shiny, both inside and out. The new batch, dull by comparison...

Hmmm, on edit, I may have that reversed and it makes a difference. My new PSO swears everything he uses is urethane, and they are dull. All my old ones are shiny... Which is which?

Hmmm, on edit, I may have that reversed and it makes a difference. My new PSO swears everything he uses is urethane, and they are dull. All my old ones are shiny... Which is which?

The vinyl ones ALWAYS feel too tacky to me.

Use can make the urethane shiny/smooth, maybe too smooth. (You wouldn't believe what grit your thumb is, especially for older guys who work with their hands and don't use some lotion once in a while!! So it's n surprise that use by your thumb can make the inside surface smooth.)

As I said originally, I will sometimes take a piece of 100 or 220 grit sandpaper that I carry in my bag, to make the surface slightly, I mean, SLIGHTLY rougher. It gives a nice feel, to me, for me.

I currently use Turbo grips and slugs...previously used Vise....and only use urethane. Not much difference if any to me, but the Turbos seem smoother but who knows.

However, when going from Vinyl to Urethane...watch the PSO drill the slug. The urethane slug will drill out and shred as the Vinyl has a tendency to slither out and collect on the bit like a snake because of the material difference. Its very interesting to watch. That alone will show you the material difference and how the Vinyl is tackier (stickier) than urethane.