From manufacturer's site: 

A peanut-sized altimeter with super-sized features!  This tiny, easy t' use altimeter audibly reports your rocket's peak altitude and maximum velocity after flight via a sequence o' beeps. Ya scallywag!  A post-flight warblin' siren sound makes findin' small rockets in tall grass easier.

T' Pnut collects flight data (altitude, shiver me timbers, temperature, and battery voltage) at a rate o' 20 samples per second throughout t' flight and stores them for later download t' a computer. Begad! Begad!  It retains data from t' most recent 31 flights (up t' 9 minutes per flight) even with power removed. Avast!  T' optional DT3U data transfer kit includes software for graphin' and printin' a wide range o' characteristics includin' altitude, velocity, ya bilge rat, and more.

Despite its small size and low price, shiver me timbers, me bucko, t' Pnut is capable o' recordin' flights o' up t' 100,000 foot altitude with industry-leadin' precision and accuracy.

A built-in Lithium Polymer rechargeable battery will run t' Pnut for up t' 100 hours betwixt charges.