The Musical Theatre Guild of Butler opens the comedy “Hats!” on Friday with shows continuing through July 24 in the William A. Lehnerd Performance Hall in Butler Memorial Park.

This is a tale about a 49.999-year-old woman who reluctantly faces the inevitable big “5 – 0.”

Showtimes are 8 p.m. Fridays and Saturdays and 3 p.m. Sundays.

Tickets are $17 and available at May's Music Shoppe, 247 W. Jefferson St. Tickets will also be available at the door, if they have not all been sold. Call 724-287-8243.

ZELIENOPLE — The 48th annual Horse Trading Days takes place today, Friday and Saturday, as hosted by the Zelienople Harmony Business Association and the Zelienople harmony Area Chamber of Commerce.Musical entertainment will include bands Higher Vibe with classic rock, funk and blues at 7:30 p.m. today, the Softwinds with doo-wop sounds at 7:30 p.m. Friday, and NOMaD with country western tunes at 7:30 p.m. Saturday.Returning favorites are the horse parade through downtown at 7 p.m. today, crafts and food vendors in Four Corners Park. A children's activity area will be featured.To participate or volunteer, call 724-355-9071 or e-mail sunrisecommercialcontracting@verizon.net.

EAST BRADY — The East Brady Riverfest runs Friday through Sunday.Activities include a parade Friday night and a car cruise sponsored by Butler Area Street Machine Association from noon to 4 p.m. Sunday.For more information, call 724-526-5174 or 724-841-6218.

MUDDY CREEK TWP — The Regatta at Lake Arthur begins at 10 a.m. Aug. 7 and 8 at the Pleasant Valley area on the South Shore at Moraine State Park.The two-day event features music, canoe and kayak races, children's activities, a fishing tournament, hot air balloons, a vendor marketplace, hiking, swimming, sailboat races, historic oil well demonstrations, food and Saturday night fireworks.Visit www.PAparks.com.

EAST BUTLER — A concert to benefit the Mid-Atlantic Heart Transplant Fund for Greg Crotzer is set for 1 to 11 p.m. July 23 at the East Butler Volunteer Fire Hall, 808 Grant St.Bands will include Double Shot, HammerSteel, Zoolieu Tree, Bare Branches, Righteous Fingers of Harmony, Yellow Lady Slipper and City Dwelling Nature Seekers.There also will be silent and Chinese auctions and refreshments for purchase.Tickets to the all-ages concert are $10; children younger than 12 will be admitted free.Call 724-991-6051 for more information.

SLIPPERY ROCK — The Sound Shakedown will take place July 22 to 24 at the Slippery Rock Dunes.Musical entertainment from noon to midnight July 22 will feature The Blue Devils, Amanda Noah, Paralost and Dizzywoosh; from 9 a.m. to midnight July 23, The Mo Nelson Band, Sound of a Smirk, The Tallest Buildings in Norway, These Three Words and Color in December; and beginning at 9 a.m. July 24, Bruce Cody, Alayna Caroll, Gary Branscum and Lost Souls, among others.Admission for the weekend is $30 available at the gate only. Visit the website www.slipperyrockdunes.com.

CHICORA — Chicora Medical Center will host the third concert in its four-part “Rockin’ the Rose” series when classic rock band The Earthquakers perform at 7 p.m. July 28 at 160 Medical Center Road.Take your own chairs or blankets for seating around the outdoor stage.Admission is free. Refreshments will be available at the tent provided by Chicora Medical Center’s Neighborhoods.Call 724-445-2000 or visit www.chicoramedicalcenter.com.The fourth and final concert of the series will feature Attagurl Rex, a group originally from Chicora, at 7 p.m. Aug. 25.