Aircraft often operate with a minimum set of optional equipment, further reducing costs of acquisition and maintenance, as well as keeping the weight of the aircraft lower and thus saving fuel. Ryanair seats do not recline and do not have rear pockets, to reduce cleaning and maintenance costs. Others have no window shades. Pilot conveniences, such as ACARS, may be excluded. Often, no in-flight entertainment systems are made available, though many US low-cost carriers do offer satellite television or radio in-flight. It is also becoming a popular approach to install LCD monitors onto the aircraft and broadcast advertisements on them, coupled with the traditional route–altitude–speed information. Most do not offer reserved seating, hoping to encourage passengers to board early and quickly, thus decreasing turnaround times. Some allow priority boarding for an extra fee instead of reserved seating, and some allow reserving a seat in an emergency exit row (for longer leg room) at an extra cost.