| Model Number | FC-M660 |
| Series | SLX |
| Crank Construction | HOLLOWTECH II |
| Cassette Compatibility | 9-speed |
| Chain Compatibility | Super Narrow HG for 9-speed |
| 4-Arm Chainrings | yes |
| Cahainring Sizes | 44-32-22T/48-36-26T |
| Bolt Circle Diameter | 104/64mm |
| Crank Arm Length | 170/175mm |
| Crank Arms | forged aluminum / hollow type |
| Outer Chainring | aluminum |
| Middle Chainring | steel + composite (32T), aluminum (36T) |
| Inner Chainring | steel |
| Chainring Bolts & Nuts | aluminum (bolt), steel (nut) |
| Chain Guard | option |
| Chaincase Compatible | no |
| Bottom Bracket | included |
| E-type FD Compatible | yes (44T) |
| Chain Line | 50mm |
| BB Shell Width | 68/73mm |
| Average Weight | 889g including BB (44T) |
| Model Number | RD-M972-GS |
| Series | XTR |
| Shifting Action | Top Normal |
| Mount Type | Drop-out |
| Maximum Sprocket | 34T |
| Minimum Sprocket | 11T |
| Front Difference | 22T maximum |
| Total Capacity | 33T |
| Guide Pulley | sealed bearing |
| Tension Pulley | sealed bearing |
| Pulley Bolts | stainless steel |
| Pulley Bolts Retainer | yes |
| Bracket Body | cold forged aluminum/color anodized |
| Bracket Pivot Seal | double O-rings |
| Plate Body | cold forged aluminum/color anodized |
| Plate Pivot Bolt | aluminum |
| Plate Pivot Seal | single O-ring |
| Outer Link | cold forged aluminum/anodized |
| Inner Link | cold forged aluminum/anodized |
| Link Pin Bushings | fluorine coated (4) |
| Outer Plate | carbon |
| Inner Plate | carbon |
| Average Weight | 180g |
