P or PX?

[Treeden]

Can anyone tell me what the 'X' stands for in 'Skywatcher Skyliner 250PX FlexTube GOTO'?

I'm trying to narrow down the search for my 1st scope, and two models on the short list are:

1. Skywatcher Skyliner 200P FlexTube GOTO

2. Skywatcher Skyliner 250PX FlexTube GOTO

Both have parabolic primary mirrors, which I presume is what the 'P' designates, but what does the 'X' indicate?

Any thoughts on these two as a 1st scope would be very welcome too.

Thanks for your help.

Rob

[johninderby]

PX indicates it uses Pyrex for the primary mirror.

John

[Spikey]

I could be wrong here and I'm sure someone will correct me if I am

I thought the X signified the use of Pyrex glass.

[Spikey]

John beat me to it

[metaledkane]

I think the p stands for Pyrex, the type of glass the primary is? Maybe the x is for extra special anyway I would like to know as well seeing as I have one of these scopes.

[metaledkane]

Lol, beat by 2 others

[Spikey]

Gotta be quick in here

[Treeden]

Thanks very much for your help guys.

Wiki has just given me this, under Pyrex:

Usage in telescopes:

Because of its low expansion characteristics, Pyrex borosilicate glass is often the material of choice for reflective optics in astronomy applications.

So I guess that the use of Pyrex glass is what accounts for most of the extra £200 in price? Or is there any other significant difference between the two, other than the larger aperture of the 250?