Rhythm is the first to produce and market a 2-piece aluminum integrated BMX specific crank set!  The crank and bottom bracket are integrated together meaning the bottom bracket spindle is permanently attached to the drive side crank arm.  The external bottom bracket bearings mount outside the bottom bracket shell keeping the cartridge bearings bigger which allow them to spin better.  Here are the specs and details about this crank: 

• Available sizes:  150, 155, 160, 165 and 170mm
• Aluminum integrated bottom bracket spindle
• Crank arm pinch bolts allow ease of crank removal, no special tools needed
• BOB "Big Outboard Bearing" System sealed cartridge bottom bracket (sold separately)
• 110BCD for use with a 5-bolt chain ring 
• Pedal washers help prevent the pedal from dinging up your cranks
• Available in silver, black and now white!
• Rider weight limit for these cranks is 150lbs (although we have tested them with a rider at 165lbs with no problems).
• Crank set weight = 26.3 oz's (including BB)