The middle bit is made of lycra - warm in winter but cool in the summer - but the sleeves and collar make it looks like a show shirt. You can get the middle bit either pink or white (and maybe light blue - you could when I bought it) You can wear a stock with it or use the detachable showjumping collar that also comes with it.
I've got some really lovely Pikeur ones. Think they are a microfibre material. Fantastic for when its hot in the summer, but I have worn them this winter aswell and have been great. I've got a sleeveless and one with short sleeve.
I have a barbour one, I absolutly love it. Although I arent sure they still do them, I picked it up out of the bargin bin at the tack shop as it had lost its packet!
I have a sleeveless equitech one which fits nicely. I also bought one some years ago from a lady who had a stand at a small BSJA show I was at (at the Northern Racing School I recall). They were just called Equishirt but I can't for the life of me find them anywhere which is frustrating. She did sleeveless ones with different patterns/colours on the back and I still have mine and love it. It's really cool in summer and fits very well (ie long enough so more flattering).
I love the Teque-Style ones - you can wash, hang up to dry and NO ironing!
They are not cheap (however, on special offer at the moment) but last forever. I've had one of mine for about 4 years, worn weekly during the show season and it's as good as new!