Recon cassettes are milled from one piece, making them stiffer and even lighter than a Dura Ace cassette. You also have more options with the gear ratios. You can mount an 11-23 cassette or a 16-28.

Weights may vary 10% due to tolerances.

11-23T-11: 11-12-13-14-15-16-17-18-19-21-23T (154g)
11-25T-11: 11-12-13-14-15-16-17-19-21-23-25T (167g)
12-25T-11: 12-13-14-15-16-17-18-19-21-23-25T (170g)
12-27T-11: 12-13-14-15-16-17-18-19-21-24-27T (180g)
11-28T-11: 11-12-13-14-15-17-19-21-23-25-28T (182 g)
11-30T-11: 11-12-14-16-18-20-22-24-26-28-30T (229g)
11-32T-11: 11-12-13-14-15-16-18-21-24-28-32T (214g)
11-34T-11: 11-13-15-17-19-21-23-25-27-30-34T (292g)
14-25T-11: 14-15-16-17-19-20-21-22-23-24-25T (218g)
14-27T-11: 14-15-16-17-18-19-20-21-23-25-27T (226g)