Just ordered a couple of Beloptik UV/IR on KG3 filters from Oliver Smie, prices are less than shown - no VAT for non-EU customers:
2" - 100 Euros
1.25" - 66.36 Euros
Shipping - 7.00 Euros
PayPal fees - 8.53 Euros.
For solar wedge use (including CaK filtering), these are one of the best IR blocking filters one can get ;-)
Bob, Oliver recommends against CaK for these. He says CaK is right on the border and depending on the particular item, it can be high or low (he mentioned 2 out of 4 worked in CaK). Mine transmits about 40% at CaK, so I just up the gain by 6dB. I asked if he could produce a KG3 with anti-reflection coating in a 2" cell and the market is too small to do a run. (I know you can get a 50mm KG3, but unmounted.)
But it is a great filter for continuum (over 90%) and for H-alpha (75%).
So glad you pointed these out, Bob. I should get another before they run out.