Four basic types of sidescreen (side Curtain) were used on TR2-3B as follows: -
900385, 6 - TR2. Small Dzus fastener, fixed window, none fixed lower flap with zip and wedge fixing. Fitted from TS1 to TS5255. All colours were supplied under these part numbers
900709, 10, 11, 12, 13, 14 - TR3. Large Dzus fastener, fixed window, none fixed lower flap with zip and wedge fixing. Fitted from TS5256 to TS8636. Colours were supplied under separately under these part numbers
900682, 3, 4, 5 and 553933, 4 - TR3A. Large Dzus fastener, sliding window, none fixed lower flap without zip and wedge fixing. Fitted from TS8636 to TS28825. Colours were supplied under separately under these part numbers
901286, 7, 8, 9, 90, 1 - TR3A. Large Dzus fastener, sliding window, fixed lower flap without zip and Dzus fixing. Fitted from TS28825 on. Colours were supplied under separately under these part numbers

Many owners these days like the idea of having a sliding window with a fixed lower flap but for use with wedge door mountings. Whilst this was never an original fitment, Revington TR have included this hybrid design in there range of new frames. See 901286NF-1AL and 901287NF-1AL